If anything, you could hold on to her and use her bow valor to farm sp on future bow units that you get. You could also fodder her off for shining bow or speed res link, however, personally I'd hold on to her for the bow valor skill to use with other units and later on decide if there is a unit that can really benefit from her fodder. You don't want to regret foddering her off down the line.
what to do with this Nina?
hey guys today i pulled a Nina but she is -atk +spd, i wanted an archer since i only have B!Lyn and Bridal Cordelia but with her IVs i dont know if she is even worth building, is the -atk bane that bad?
I say use her. Her spd is too good to pass up. Buff her atk to make up for it being low. Felicia has 26 atk with a boon with a 14mt prf and she still sometimes needs help against low def mages.
Have a look at what I wrote here.