I used to say "first, kill the Blade of Crota that spawns with him, then do unto Urzok as you do unto Crota". However, no more Blades of Crota.... So... as many arc weapons as possible, and be accurate with your damage. Try and pick an arc sniper and arc MG like Jolders with field scout alongside an arc primary. Take his shield down with your least damaging weapon then pile in as many precision hits as you can with your heavy hitters before you have to reload everything (and his shield goes up) If you haven't gone to the skywatch specifically to kill him, don't try it on the off chance without switching weapons. Urzok is the definition of OP. He's tougher than even lvl 33 Swordbearers to kill with Guardian weapons. He used to take more hits with the sword than lvl 33 Gatekeepers. After all, he is the Hive's own Executioner... he's gotta be tough