About to +10 Eirika

This is what I'm doing with my Eirika (not +10 yet though). She has pretty decent mixed bulk, so I think -HP is the best bane. And you want to push that stats further up, so Fury is a good option. I don't have Distant Counter fodder, but if you do, she can make great use of it due to her decent RES. My Eirika is on a Tactics team, so she gets +6 to every stats, and another +6 in combat, bringing her overall stats to 68/54/45/46 at max merge. That should be good enough.

Sieglinde turns Eirika into a super tank who can take multiple hits, so she'd definitely prefer the HP bane. She still has 46 at full merge, which is plenty.

It's hard to pass on the Atk superboon. Sieglinde can easily get her Spd into the 47-50 range even at neutral, so the boon is probably overkill here. Still, it's an option.

I see you too are a man of culture. In all seriousness though, while basic this build works great on a tactics team. She's +atk/- hp btw. Also can't wait until she gets storm seigelinde, I think it could open up some different build options for her compared to what you usually see.