Who makes better use of Atk Tactic?

I would say either Myrrh or F Grima. Having more mobility is kinda huge and allows them to buff more often. As well as that those are the two that don't really need the attack boost too much. I'd say myrrh is a little better since F Grima has lower attack but either works. Nowi's attack is generally ok at best since she is forced to use a low mt weapon and M Grima is an attack stat beast so he always likes more. Normally I would say give it to the unit with the most attack, but in this case M Grima is an armored unit and thats really inconsistent. So yea, go for Myrrh or F Grima.

It depends on the builds, but I would say either nowi or grima. If you're running a vengeful fighter build on grima or a steady breath+QR build on nowi, they can rely on their specials rather than their attack stat for damage. The others don't have access to special charge reduction and definitely need as much attack as they can get