Since I played both, I’d advise you to pick doppel over fencer if you have not decided yet.
True, Sept etoiles, flash and composee can be copied which are core fencer skills and throwing them all off in a bunshin destroys bosses, but other than that your damage isn’t really that good compared to a doppel.
You may also have to cheat bunshin cd by using: Sept once, Flash twice, Composee 4x, Kunai 2x, Katon 1x. Flash has terrible cd when paired with bunshin penalty.
furthermore, fencer requires you to crit to get that bonus, for doppel just dov and it’s always there. of course critting on doppel is also nice, but for fencers it’s much more crucial.
btw don’t follow the skill build I posted above, it’s for my own personal use, I’ll update the guide for general use and let people adjust accordingly with their playstyle. But if you want to follow my personal skill distribution go ahead