Once per turn when you deal damage to a creature with an attack using a weapon, you can target the creature where it is most vulnerable to gain the following benefits.
Damage Vulnerability
Choose one damage type dealt by the attack. The target has Vulnerability to the chosen damage type for this attack. Vulnerability from this feature doesn't double extra damage from spells (such as Hunter's Mark) or features from other classes (such as the Rogue's Sneak Attack). The Vulnerability doesn't apply to this attack if the target has Immunity to the chosen damage type.
Disrupt Resistance
If the target has Resistance to one or more damage types, it loses these Resistances until the start of your next turn, including against the damage of the triggering attack.