Elder-Basilisk said:
Modern soldiers wore helmets and body armor even when they weren't at all likely to stop a bullet because they would stop shrapnel and even that much was very useful.
I guess, even against guns it would be better to be wearing some sort of armor that to go completely naked. Even if it would only stop extreme range hits, ricochets, or shell fragments. Players are notoriously cautious and will do anything (such as sleeping in armor) to improve the survivability of their character. The best thing to discourage armor use (if that's what you want) is to play up the reasons armor gradually faded away. Here's a list of reasons I can think of ...
1) Its hard to breath in a closed helmet.
2) Full armor builds up heat rapidly.
3) If you fall in mud or water it might be difficult to stand back up again. Same if you are being grappled or pinned down with pole arms.
4) Full armor slows movement which increased the amount of time it takes before you can close range with guns or crossbows. This lead to legless half armor which was popular with infantry.
Pike formations led to the gradual dismounting of heavy cavalry where these problems went from being inconveniences to huge problems. You would still see some sorts of armor on cavalry until the 1800s.
#3 is taken care of with armor check penalties and #4 with movement decreases. For #1 and #2, I was thinking of making a limit such as 1 round per point of Con that you can fully exert yourself, such as being in combat or running, before being fatigued*. Thus the agile fighter can wear down the armored knight, possibly turning the tide.
Aaron
*The 8 hour recovery time is probably too harsh.