Armormech's Celerity

Armormech Engineering: 14th and 17th level When you take the Attack action or use your action to a cast a tech power of 1st-level or higher, you can make one weapon attack as a bonus action. You can use this feature five times. You gain an additional use at 17th level. You regain all expended uses when you complete a long rest.

Granted by Armormech Engineering at 17th level.