One of the things that's required when making a game with modern and scifi elements "100% compatible" with a fantasy game like Pathfinder is to model more advanced gear in terms of how it works and interacts with swords and chainmail. Luckily most practical questions -- how much does it weigh, what does it do to my AC -- are the same for fantasy and more advanced gear.
We'll be working on and playtesting a lot of our gear descriptions as time goes on, but here's a preview on one such item -- the modern riot shield. (And more "Anachornistic Armor" will be available very shortly as a $1 'Bullet Point' PDF, for people who want to see more of our current thinking on the question.)
Riot Shield
Armor Type:
Shield Cost: 300 gp
Shield Bonus: +1 Max Dex Bonus: – Check Penalty: -1 Arcane Spell Failure: 15%
Speed (30 ft.): – Speed (20 ft.): – Weight: 5 lbs. Hardness: 8 hp:
3
This is a clear plastic shield designed to protect against
rocks and similar weapons of opportunity. The shield runs from the wielder’s
shoulders to just below his knees, and is wide enough to offer good protection
for the body. Its shield bonus is increased by +1 (to +2) against improvised
weapons. The wielder may do nonlethal damage with shield bash attacks without
taking the normal -4 penalty to do so.