Helswath is an A rank throwing axe you get through normal play that adds 5 DEF. It's basically one of the best weapons around, even including Brave weapons because of its high Might + DEF bonus + 1~2 range.
And if it's Chrom, with the classes you already excluded, I'd probably just go Swordmaster or Warrior on him since those have the next highest Skill caps to add to his higher skill proc rate.
Probably Swordmaster so you can have Armsthrift + Amatsu + Swordmaster. Amatsu being a 1~2 range physical sword.
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