Info on ancient armor/weapon?

[Ivonia]

Is there any website (or relatively inexpensive book, like under $50) that describes various types of weapons and armor as well as what they're strong/weak against?

The talks about fighting has got me interested in writing a fantasy story for one of my classes this semester (a fiction workshop class yay ), and I would like to be as detailed as possible (at least so that instead of "the hero then put on his armor", I can say something like "the hero only wore a short sleeved chain tunic, since that was all he could afford at the present time"). I know that in history, most soldiers couldn't afford to be outfitted in full plate armor most of the time, so what did they wear (or did they really go and fight with nothing more than the clothes on their back)? Did the enemy often use armor they acquired off of dead foes, or did they take it and use it for something else (like melting it down to make a weapon?)

I'm particularly interested in medieval plate armor (and any armor for animals as well if possible, as I intend on using armored horses and perhaps elephants as well).

Weapon info would also be cool. For instance, a short, 1 handed sword might not be too effective against a shield (particularly those large heater ones), but a big, 2 handed hammer would probably break that same shield (not to mention the defender's arms/bones) after a few blows (cause I imagine there's a lot of force being delivered by that small head on the hammer). A longbow would probably screw up anyone that gets hit by that arrow, but if any infantry does manage to make it to the bowman, I suspect the archer wouldn't be able to stand toe to toe with them for long (guess asking this after watching Braveheart hehe)?

Any help on this stuff would be greatly appreciated