Damage Over Time keeps his shield from regenerating as quickly between barrages. There are many ways to achieve this, get creative.
Also, if you're lucky enough to see a Pack of Wolves in the area, for gods sake, save the scorch cannons for mister big tough guy.
Just stroll in by yourself hit him with some arc damage until his shield is down then one shot him with Celestial Nighthawk.
Video from ARandomPanda44
http://xboxclips.com/ARandomPanda44/186ee577-0672-45d2-aa02-51891a3f80db
Equip arc shotgun and arc rockets.
Wait for him to spawn.
Unloads rockets first then Finnish off with shotgun - screw the public event part just camp for him
Arc weapons arc weapons arc weapons. Oh. And do hit and runs because trying to juggle him, 2 other pissed off Knights, and the Fallen is annoying. Actually. More impossible