Mettle Finesse (4e Feat)
From D&D Wiki
You deal more damage for maximizing your mettle spending.
Prerequisite: Lioneer, mettle class feature
Benefit: Whenever you spend the maximum amount of mettle points allowed on an attack, you can add your Dexterity modifier to the damage roll. This bonus increases to 2 + your Dexterity modifier at 11th level and 4 + your Dexterity modifier at 21st level.