First, Forehead Protector Pic and Weapon/Armor Pics would be completely different, I say if you want to show a picture of them, have a link to them in your personal website or something, and save server space, and space in your Bio.
And say we did put them in, how would you fit them into your Bio? next to your avatar? bottom of the page? Where?
Also you say that most people have a custom Weapon and Armor... I don't and plenty of people I know don't, most of us think it is a waste of DP as it provides no real improvement to your character, it's purely cosmetic, and not many see it unlike Name colouring and titles. Most people I know that buy them have heaps of spare DP.
Last, showing your specialty in your bio is bad, one like Rai said you can have multiple specialties at once, which could easily be solved by just showing the current one.
The actual problem with it is that anyone can see what every one is using, and I know that most experienced players seem to pick pretty much Specialties, so it would be easy for anyone to see and go, well everyone is using X Specialty, maybe I should be to.