Best H!Henry tome/build?

If you're running him on an Armor Emblem team, and you're running Hone and Fortify Armor, then Gronnblade will be helpful to you (as long as you don't get hit with Panic).

I don't really see any Henry's with Gronnraven since most armored units can obliterate Lyn anyway, so I dunno.

He is an absolute powerhouse in terms of tanking mages. I'd just stick with owl, however, as you could bolster his defenses to insane levels.

If you're running him with triple Ward Armors, go with Gronnowl, and he'll get 40/58 when everyone's adjacent, but he'll still only have 45 attack.

If you're running him with Hone Armors and Fortify Armors, running him with Gronnblade will give him +30 attack, but leave him at 28 defense.

Mine will be run with Gronnowl+, but he'll have CC and he's +Def -Atk.