Pity Breaker Elincia?

I pulled my second Elincia today while looking for Tharja.

My first Elincia is -spd, +Def.
This second one is -spd, +Hp.

Do I merge and keep the +Def nature? Do I inherit Flyer Formation to somebody (if so, who)? Or do I level her up and build her with different skills for flexibility in arena assault and potentially a double Elincia team elsewhere? Until I get 42 more Elincias and build a hypermax Elincia spam team of course.