Silver Eagle Weapons

Alter: You gain a +1 bonus to attack and damage rolls made with these silvered magic weapons of elven make. These weapons deal 2d6 damage instead of their normal damage dice, and landing a critical hit with the weapon doesn't double the weapon's damage dice. Whenever you land an attack with the weapon and roll the same number on both of the weapon's damage dice, you can immediately roll another d6 and add it to the weapon's damage dice. You can continue rolling extra damage dice until you roll a number that does not match the previous rolls.

Attunement: No
Rarity: Uncommon
Type: Greataxe, Greatsword, Lance or Maul
Cost: 170gp

Griffons Saddlebag, Vol 1

Edit: in exchage for not being able to crit, on a nat 20 the player (or DM on a nat 1) pulls 3 cards from the Luck Deck, and selects one. it must be used before the players next turn.

in world as a sort of " the attack was helpful, allowing X to get a better hit", or "missing the blow causes you to stumble into X, knocking their attack off a little"