Not sure if I want to keep Laevatein

Now that my realization that I need a Surtr for fodder has pasted, i need to ask this.
I got a Laevatein this L!Banner and she's +atk -def. Really good IVs, spectacular even. But the thing is... I really don't know if I need her. I already have a great amount of sword users who perform just fine like Zelgius, Marth, L!Ryoma, Caeda, Navarre (yes Navarre), and more. Plus I'm REALLY tempted to give L!Ryoma OSW. I know I'd be a bit over kill since he's +spd, but it'd give good buffs to a team he's in.
Idk, should I sack her or keep. The answer is probably obvious but I need just a small bit of convincing.