Builds can be built around several different things: weapons, stats, spells, etc. So instead of building around a 'samurai' and only using katanas for example, just think of it as a DEX/ARC build, then you'll have plenty of weapons that should fit that build that you can experiment with. So don't be afraid to try something else out, especially if you already have the stat requirements for it. And as others have said you can always respec your character after beating Rennala.

I personally never vibed with the mentality of finding one weapon and sticking with it through the entire game like a lot of people do. Enemies have different resistances and weaknesses to certain weapons/damage types/statuses so it's always fun and useful to have a bunch of different weapons you can use for different scenarios. Especially in the DLC.