I have been running Res +10 with mine, and I kind of think it a bit redundant since you have Aegis. It does help with the occasional Levin Sword but I think Aggressor or Luna works better. Aggressor, while better with a Galeforce user, is nice with Chrom since he can proc Aether. I generally have bad luck with it, so I think Luna might be the better option to have some sure fired damage output.
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