Empire is right. The main problem is that the initial paragraph is not in POV. But much of the language used is...sound and fury.For example, "The mud soaked ground lowered itself when the weight of a soldier’s boots fell on it." This is not what happens. The "ground" does not lower itself, nor is it "soaked in mud". It is either muddy or covered with mud (a bed of gravel can be "soaked in mud", but few other floors plausibly can, and mud soaked gravel doesn't tend to give way under load anymore than regular gravel, anyway). And it "squelches" or "gives" rather than "lowering itself."
Anyway, even fixing all that, you have to extablish first who's eyes you are seeing all of this through first. The fact that you describe things about Diego that he would be unlikely to notice (or even be in a position to notice, like the color of his eyes and face) tends to divorce the reader from his POV.
The third paragraph is really quite good, other than the fact that you have Diego think of his posture as "statuesque." Thinking of oneself that way, except when practicing in front of a mirror (or even then, really) doesn't befit a warrior or leader of men. But the whole contemplation of House Avalando and why they would challenge De la Cruz is perfect POV, and very appropriate.
Don't need to harp on the POV voilations of having a character think about his own appearance for no reason. But you can give a character reasons to think about the cut of his beard or the color of his own eyes. For instance, when commanding a person of dubious loyalty or courage, he might be very conscious of exactly what image he presented. Or he might think about it off-hand while brushing mud from his clothes, considering the importance of a commanding officer who at least appears to be in command. There are plenty of reasons that a character might think about what they look like, but remember that portraying a man thinking about such things influences how the reader percieves him (and not always in a good way). Also make sure they the POV character describes what he thinks he looks like, not what he actually looks like...back to the story.
Archerers should be placed behind foot, never in front. If the enemy were to launch an assault, the archerers would be slaughtered unless the main body broke ranks to let them retreat, in which case the main body would be slaughtered when the enemy charge caught them with broken ranks. Also, forcing the archerers to look back over their shoulders and away from the enemy for a release signal is deeply stupid--when commands must be relayed to troops in the front, it must be by music (drums, pipes, trumpets) or rallying cries (A la Cruz! ).
Range of a good cross-bow or composite bow (which your troops are not equipped with) is between 100-300 meters for firing at individual targets, and for firing at a large body of men it is more like 500-1000 meters. For a longbow such as your men would be using, the range for effective mass fire at an enemy army would be 300-600 yards. The distance of a cavalry charge is perhaps 100-200 m, the distance of a foot charge is less than 100 m. Therefore, there is never any reason to advance the bowmen in front of the foot. Also, you can leave a bow strung all day without weakening it appreciably, so there is absolutely never a reason to have them meet the enemy with unstrung bows. Perhaps you mean "the nocked arrows and raised their bows." I will not go into the technical aspects of this, but the proper method for drawing a longbow is to nock the arrow, then hold the bow up so that the arrow is pointed directly up and the string is parallel to the ground. The limbs of the bow should be alinged with the shoulders, the top limb pointed over the shoulder of the drawing arm (the right, for a right handed bowman). The other arm (the left) should be straight and vertical, the bow resting lightly in crotch of the hand, fingers lightly curled (curling the fingers is not actually necessary, many target archerers do not curl their fingers, but in a battle you wouldn't want ot risk dropping your weapon). The first three fingers of the drawing hand (right) should be holding the arrow nocked to the string, with the arrow between the index and middle fingers, and the resting against the inside pads of the second knuckles (many archerers use a leather pad or finger gloves). The bow arm (left) is then brought down into a horizontal position, kept straight out to the side, and the drawing arm has only to maintain a line moving down vertically, thus drawing the nocked arrow to the ear of the head, which must be turned to the side so as to align with the direction of the arrow. When the proper position is reached, the arrow is released (it is true that historically, some armies practiced forcing the archerers to hold the nocked and drawn arrow till the command to loose the volley was given, but I think that is a stupid practice...arrows have different flight times anyway, so you will not achieve a simultaneous impact in any case). Okay, that was more than you ever wanted to know about archery, most likely.
The tenth paragraph has to much use of the word "he", particularly at the beginning of sentances. Also, you have him order the archers (still standing in front of him, and thereby obliged to look over their shoulders to see his signals) to "fire at will". This is not accurate or tactically sound. The effect of a massed volley of arrows is magnified by the fact that you cannot dodge the individual shafts, because you just end up in the way of another arrow. With continuous fire, it becomes possible for alert warriors to dodge (or deflect) individual shafts, and so the effect of the long range shots are limited. Worse, it is difficult to give orders to troops that are engaged "at will", thus, when it comes time to advance the foot and cavalry, there will be confusion and delay (particularly since, as you have posted the bowmen in front, the enemy can assault at any time, forcing you to withdraw or sacrifice them). You are also presuming that the men of Avalando have no shields--which seems insane in an environment where bowmen are employed, but I suppose it's possible--which leads to an unrealistic slaughter. The main effect of a good volley of arrows is not casualties, but disruption of the enemy ranks, and forced commitment to the passive defense of hiding behind shields. This disorganization should be capitalized on by using the cover of massed volleys to attack the flanks with cavalry while charging the main line with foot (numerous variations are possible, and between evenly matched forces there will be an "archery" duel as well as cavalry engagements off to either side of the battle before one side or the other is ready to commit for a combined assault).
Contrary to what C of E said, steel was around in the middle ages (heck, even the Romans had steel). I think that he is thinking either of stainless steel (actually, before the development of Iron and steel technologies, the only way to get steel was from meteorites, which often have high nickel content, resulting in many bronze age and earlier artifacts being made of stainless steel...though of course such things would be rare and extreemly valuable) or of industrial steel produced using the Bessemer process.
On the other hand, he is right that bowmen would not draw swords and be committed to the assault. Bowmen typically fought behind pikemen or fortifications, and were only armed with a short sword--if that--for close quarters battle. They would not even be ordered to stand and recieve an assault, since they wouldn't usually have shields sufficient to stop more than arrows, if that.
Cavalry should be armed with lances for fighting footmen from horseback. They are also equipped with heavy sidearms, but these are for use against other cavalry in the event that their lances are broken or for fighting afoot if they are dismounted. Horsemen cannot easily fight footmen with swords, unless they "ride them down," that is, pursue them in flight and overtake them as if to pass on the left (or right, for a left handed knight) hand side. At that point it is possible to strike with a sword or other sidearm. On the other hand, a knight armed with a lance can bear down directly on an opponent, lance him with great effect at a distance of 2-5 meters, then heel off to attack another opponent (lances can also be used to "ride down" fleeing foot more effectively than sidearms).
Okay, I have to agree with the others that "Inquisitor" is a bit over the top. So is a commanding officer leading from the front against a demoralized and fleeing mob that should have been mopped up by the cavalry already. In addition, you have him give the order for "no quarter" and running out ahead of everyone, but then he turns his back on the first opponent to offer him battle.
Okay...to sum up, I really actually like your writing, but you haven't the least clue what your talking about, and it shows.
The whole part where it turns out the entire enemy army is a feint, I will grant as an interesting and plausible (barely) idea. But the fact that everyone in this army apparently knows that they are just a sacrifice is completely beyond belief. What could possibly motivate that number of people to be willing to die just for a feint, and why use such highly motivated troops instead of innocent dupes? Also, a feint that can be defeated so quickly isn't worth the cost in blood, a small raiding party would have had a better effect and been less costly. Even better, a feint that went out and then retreated as though fearing battle, thus inviting pursuit, would draw Diego even further out whether or not he brought them to bay.
And why is this expensive diversion even needed if the real assault is going to be made by an assassin using poison? A woman, at that, posing as a maid. No number of soldiers milling about in the palace would be the least bar to her or the least help to the victems after they were poisoned. It makes even less sense than a vainly overconfident House Avalando challenging De la Cruz to battle in the mistaken belief that they are on their way up.
The scene with Ezmerelda was also flawed. For one thing, a poison candle...you need to do some serious research. Her attitudes also seem really strange...actually, you need to work on the entire culture, some of Diego's actions and words were equally strange. But Esmerelda had a really strange attitude towards her own culture...you will need to clarify if she is supposed to be an import from some exotic land or something...and if she is not you will need to justify her having that attitude towards her own culture (I know that it is common for modern people to feel that way about our "own" culture, but that is because they are deliberately taught to think that way in school, and even then, they rarely question the culture they really belong to).
Basic researh issues. Type "medieval weapons armor tactics battle culture history society" into a good browser, or just try the library. You should look for a couple of real examples of Machiavellian schemes and plots as well, to get some better idea how to set things up. Research medieval poisons too. Plants and tinctures that make poisonous fumes existed, but it would be difficult to make them into a candle. Incense would be the form that such a weapon would have to take (the flame of a candle would tend to denature and burn any toxic fume being emitted by the wax, and since the impurity would make a visible discoloration in a candle, it would be too easy to discover).
Your problems with florid, silly sounding language were pretty minor. Just try not to be too affected in your usage and imagery.