Br Bow outclasses Br katana when it comes to pure bossing, especially ones like Loser if you're comparing both weapons. When it comes to other things like mobbing and things like MPA FF/UQ farming because mobs will die fast and bow is a slow weapon when it comes to those things.
The only thing katana may have something bow does not would be katana combat, which enables you to just burst with no repercussion. Only thing that holds bow back would be being able to manage your pp and also knowing the nuances of the weapon.
Bow is relatively safe if you know what you're doing, you can dash dance with bow to avoid getting hit and once you can get Bomber Type-0 from crafting, that skill is great to use to dodge attacks that have longer frames than your dash.