Ethlyn

I'm pretty sure most people foddered both. Spd/Def Bond is popular. Most sacked their first off to Sharena. Nephenee also saw a lot of love for that skill.

I made my first one to be a Bowcounter and my second will be used as a merge.

I always keep 1. Always.
Need my collections.

But I think that I won't merge the other one into her. It's a rare skill and she's not worth enought to build.
A few of the free units I don't keep all copies are:
Ethlyn
Kana
Canas
Marisa

But I'll never fodder my last copy

I built up the 5* version because I love the Geanology characters and am trying to build up all of them. She's not the best healer but she's decent and has a bit of bulk, though not much on the magic side. I kept the 4* copy because I'm unsure if I want to fodder her off

Spd/Def Bond is a good skill to inherit but I would strongly recommend you not to fodder her for Heavenly Light, that can easily be obtained from a 4* Nanna (also Drive Def 2) and better yet, a 3* Wrys who can be picked up from those 1-2* free unit rotations on the special maps menu

I'm hoping for possible information about getting TT (and GHB) units as Manuals, so I wouldn't feel bad foddering her off for her Bond skill. Until then, she'll remain in Barracks limbo.