Shield Swipe is pretty mediocre, especially when you consider it in the context of paladin, which already lacks good WSes and does pretty poor damage while tanking. Plus, it's one of the very few reaction abilities in the game (the other being Haymaker, which also has an added effect that doesn't work on anything in full parties) and a level 30 quest skill. This ability could possibly add some cool gameplay and decision making to paladin if it started a combo or something. I really hope they rework it or make it a combo starter in the expansion. Doing very slightly more damage/gcd than the full Halone combo doesn't really justify its existence imo.