Armor Bane

You master the Light Hammer, Warhammer, Maul, Flail, Mace, Morningstar and War Pick. You gain the following benefits when wielding one of these weapons you are proficient with:

• You have learned to use some of these weapons more efficiently. The Morningstar gains the Versatile property when you wield it doing 1d8/1d10 piercing damage. The Mace gains the Light property when you wield it.
• The range of the Light Hammer increases by + 20/+40.
• When you get a critical hit with one of these weapons, you can choose to knock the target prone. In addition they also take an additional die of the weapons damage.
• Once per round, when you hit a creature wearing heavy armor or has an AC of 20 or more with one of these weapons you may reroll the damage dice and take either total.