Some weapons were historically designed to penetrate armor like the crossbow, so you'll see an entry for "DR Pen": Damage Reduction Penetration: this removes some DR bonus, and if the DR Pen places target into negative territory for protect, then apply that as + to damage.
For example, if wearing a leather armor with a DR 1 (non-magical), and you are hit with a Lucern Hammer that has a DR Pen value of -2, it does an extra +1 of damage as it not only negated your DR for Leather on a hit, but its kinetic energy is amplified.
The crossbow's main advantage over regular bows was its ability to generate much higher draw weights - often 200-1200+ pounds compared to a longbow's typical 80-150 pounds. This massive force, combined with heavy steel bolts (often called quarrels), made crossbows devastatingly effective against mail armor and later plate armor.
Medieval armorers and crossbow makers were essentially locked in an arms race. As armor got better, crossbow technology evolved to counter it. They developed specialized armor-piercing bolts (or quarrels) with needle-sharp bodkin points, reinforced crossbow prods (the bow part), and mechanical aids like windlasses and goat's foot levers to cock these incredibly powerful weapons.
The crossbow was so effective against armored knights that it was actually banned by the Pope in 1139 for use against Christians (though this was largely ignored). It democratized warfare in a way - a relatively untrained crossbowman could take down an expensively equipped knight who'd trained for years.
For a list of armor, gear and equipment either consult PDF Armor and Gear of use Character Generator, tab 5 Equipment Character Generator