Eirika: Restoration Lady - Merging Question

If you merge into a new copy of the same rarity, all previous merges will carry over - for example, if you merge 5*+9 into an unmerged 5*, you will have a 5*+10. Any skills you had on the 5*+9 will also stay, as well as blessing if the unmerged 5* has no blessing.

Eirika has some OHKO potential but what makes her especially powerful is that if she double-dips the +6 buffs she will hit hard (maybe not hard enough for OHKO, though sometimes yes), hit twice more often than not, and she will even tank well with mixed defenses in the upper 30s. Even most armours can't do that without both bold fighter and QR seal, which is an expensive setup - bold fighter is only available from 5* exclusives (so unless the unit comes with bold fighter you would have to sacrifice a Hardin or W.Lissa or B.Hector or L.Tiki), and each player only gets one QR seal for an entire barracks. And once they drop below 70%HP, QR deactivates, whereas Eirika will continue to double using spd.

She's not like Laevatein. Laevatein hits extremely hard, like, insanely hard, potentially the equivalent of 90-to-95ish atk without a special, which I believe is the highest in the game by a margin of around 10 points. It's definitely enough to OHKO a lot of units including potentially even bulky units like Zelgius. Eirika will cap out in the mid 60s, or maybe 70ish with full merges and an extra drive atk or something on the team; she can OHKO units that aren't as bulky, but her limit is significantly lower. But Laevatein will have a hard time getting her spd over 44 without merges even if she has +spd, and more than a few units can reach 40 spd and avoid her double. Eirika will get her spd into the upper 40s, even 50+ with merges, and once you pass somewhere around 47 spd you'll find that the units with middling spd, who can hit 40 spd, have a hard time keeping up to avoid your doubles even if they try. So Eirika will hit twice, which already means extra damage, but it also means she can charge up a special for even more damage, which probably means she has potential to get through units even Laevatein cannot.

I apologize if I'm getting a bit ahead of you there. But understand that 40-48 is a highly contested spd zone; a lot of fast units get there and they're all looking for ways to double each other. Some of them just say "screw it I'll just block your double and QR back" and settle for something like 44 spd. Eirika definitely has the potential to come out on top in this contest and double some of the fastest units in the game. She doesn't need to rely on OHKOs as much as Laevatein.