Well the thing is that you can't make the weapon better or worse than Ifrit/Moogle, it needs to be unique in it's own way. Ifrit focused on ATK, Moogle has Acc./Crit. The question is, what beneficial stat will Garuda's weapons have that makes it unique in it's own way.
Perhaps it will give you bonuses to your primary and secondary stat. Maybe perhaps (Only an example) you could have the spear with +20 STR/+20 PIE. Not the best idea, but I am kind of stumped on how these weapons will be unique among others.