Short answer:
you dnt need potency, lets get that out of the way
whatever u need to get him 220+ speed (or whatever speed to be faster than the other cls in the arena close to your rank)
A bit more elaborate now:
If u can do the above with a crit dmg set, do so <== thats 1st option
If not then use a speed set
Circle: prot primary // triangle: crit dmg primary // arrow: speed (duh xD) // cross: offense or prot (whichever provides the best overall secondaries)
for my standards in arena, i need a 250+ speed cls
I need a speed set to achieve those speed so thats what i have on him, the other 2 mods dnt matter at all(couldnt bother making a health set or a crit chance set or whatever)
https://swgoh.gg/u/lightofheaven/collection/238/commander-luke-skywalker/
currently im farming crit dmg mods, when i can form a crit dmg mod set with good secondaries (to keep him at 250+ speed) its what im aiming for