I used to think conviction is garbage, but then I did several runs on single player
Fdin with lvl 44 FOH (easily reached at this state of ladder), and conviction, destroys P7 chaos as fast as hdin, if not faster
The primary bottleneck for Hdin was the hammer takes awhile to travel
For Fdin this is less of an issue because 1 FOH will scatter holy bolts all over the place
He has less damage on paper but hits more enemies on screen