Realizing how strong this card is requires remembering a key rule. "A player controls any upgrades attached to characters they control."
You should not be exhausting your hero's personal weapons into Firepower unless your weapons don't already don't exhaust (like Valkyrie).
What you should be doing is exhausting Sidearm and Energy Spear. Load up your allies, and then unload them all simultaneously for up to 9 damage! Pay for it with Aggressive Energy or other boosts to add 3 damage for the price of one boost!
This card is not for every Aggression deck, but if you have non-exhausting weapons or allies that like to hold weapons, this might be for you!