This definitely fits thematically but I don’t know how well it’d work balance wise. A “free” +10 melee defense would turn into +20 and this would mean nimble characters could apply their stats elsewhere and be even more powerful, further reducing the advantage to going non-nimble. But at the same time you’d lose the +25% damage and the ability to tank any enemy with an axe as even the measly hatchet could destroy your buckler in 2 chops which would increase the need for a shield based tank character for enemy axemen. This idea would be neat to playtest. As it is right now I only use bucklers for my early game and as part of my melee equipment for some of my crossbowmen. But then historically, the arming sword and buckler were a side arm combination of archers anyhow so in that regard the current system also fits thematically.