SCP Foundation

I'm actually surprised this doesn't exist already. I could have sworn I read an article already of a suit of armor taking possession of a person, but all a search has provided me with today is 912 and 572. So please don't quote me on this, and I honestly would recommend asking someone else again just to be sure before proceeding.

The premise is fairly solid, there's a few things I spotted that need addressing:-

Gives host increased human ability
Hosts are physically and mentally deprived as if being fed on by the armor

These are in contradiction of one another. Is the relationship between SCP and subject mutualistic, commensalistic, or parasitic?

If bested in duel the armor crumbles to dust releasing the host

If you wish for it to have "Safe" containment class, but it crumbles to nothing, then its effectively neutralized itself upon a single defeat, and thus Foundation have nothing to contain away. Rather, the subject should wither away (or be released), not the object.

One armed guard should stand near the box to keep it secure

If the armor is looking for a host to attach to, then part of the containment procedure should not be providing it with what it needs to become a threat. Unless the rule of the object is, it must always have a host and will always have a host. In which case a D-class assigned to it, within a locked room would be more applicable.