There is also plate armour and plate armour.

The armour i envision the steel fist wearing is often referred to as munitions plate.
It's a cuirass, often with tassets (the things hanging unto the legs) that is made in bulk. Either it's the training pieces of armour apprentices, or the actual thing a foundry produces.

One of the most expensive parts of armour is actually the polish, so if you want to show off, have the troops sport armour with a literal mirror polish.
Other nobles will be mad envious.
So seeing that the force is small (compared to other in world forces) and the family is very rich and on top of this see it worthwhile to spend on its army, i say that a large portion of the troops can have plate armour. If the family invest heavily in the army, it can give fitted field plate to basically everyone.

The usual way to get troops though in the middle ages was through the feudal system though, where landed knights where duty bound to show up with at least himself in a certain degree of wargear. 
Knights being sensible, they wanted to live afterwards, so they often invested in plate armour. (I'm thinking of the 1400's ish here.)
Technology has advanced so much, that large steel plates are easier to make and the steel production is larger so it is not as expensive as before to have plate armour.
It was still expensive though.
Some landed knights however, had very wealthy land, or felt that they REALLY wanted to invest in troops, and elite troops at that.
They got hold of a few men-at-arms, basically people the knight found interesting for the task, they fund their gear and make sure they are trained. Then these men-at-arms, whom could be better at fighting than a knight, they are career soldiers after all, joined their lord in combat. Often they all had horses ass well.

Based on the info blurb on the perry miniatures men-at-arms boxed set (whom go for a very historical approach) about 4 men-at-arms to every knight in service at the time of 1400 ish. In french and english armies.

All of which wear plate armour.

Thing is, the De Reimer is the richest noble house in the setting, its army is comparably small but well trained.
When the investment has been made to have well trained troops, it only makes sense to go all the way and give them the best armour as well.

Sure, when it comes to plate armour, there is almost no upper limit to cost, but plate armour with a regular polish (satin, it looks almost white, but doesn't mirror well) will cost a bunch, luckily for the De Reimer, they have several bunches of money available.

So if you want them in plate, give them pate. Foot knights are a good indication. I use the war of the roses as an info source since it was a period in time where plate armour was common on the battlefield. In contemporary paintings the entire armies were depicted in plate.
While this is silly, there was a lot of plate armoured men in those wars.

I am rambling!

Btw, regarding the battle which Claus was in, there is a reason why i felt that as long as he got out quick, 5 enemy troops couldn't take him down. Claus wears high quality plate armour, and is literally a demigod of battle (ok, jokes aside, but he's darn good).
Plate armour is very good, against poorly trained troops with improper weapons it's OP as shit.
You need good wrestling skills, or armour piercing weapons to properly take down knights or men-at-arms, failing that you need to literally drown them in troops, throw the to the ground and stab them to death with knives.
All the while suffering horrendous losses.

Also, firearms didn't kill plate armour, economy and training time did.
Early firearms won't penetrate good plate armour unless it is weakened first. Unless we're talking about cannons, then this happens.
[img]http://i.imgur.com/ot73yZV.jpg[/img]

Rambling over, if you want i can keep rambling.