Who to give Brave Bow+?

Personally, I would give it to Cordelia, if only because Atk boons are better than Spd boons for Brave builds.

Brave Lyn. She can get Hone Cavalry from a partner for almost guaranteed quads at high power, and Sacae's blessing means no DC to worry about.

Bridelia or BLyn. Your choice. Setsuna's not the best option for it now. Brave Lyn does well without it already, sometimes slightly better with it. Bridelia gets way better with either Brave Bow+ or Firesweep Bow+. Bridelia's likely the option that's gonna make a bigger difference for you.

I would say brave lyn, due to the fact that you have the exact IV mine has and shes good with that IV for it, 36 speed and able to hit 40 damage not including A skill, but with that def bane i would say LaD can now be considered an option and it fixs that speed and +5 atk, its not like she can take 1 hit from physical or magic anyway unless buffed.

Brave Lyn, I think she's slightly more consistent with it and Cordelia works well with a firesweep bow.