Comparing this card to aggression attack events, it deals one less damage than Uppercut, or two less than Melee and Into the Fray. Giving yourself a Tough status card is surely worth more than 2 damage so arguably this card is on a par with Into the Fray.
Protection already had two good attack events in Momentum Shift and Tackle. For heroes with a good ATK value (Hulk, She-Hulk, Thor, Spider-Woman, as well as Drax), Leading Blow is a better version of Skilled Strike because you can split the damage across two targets. I think we have the tools for a new kind of deck that looks green but feels red: Christmas has come early!