You might still be able to have a nimble swordmaster – only this time he can be armed with a shield, and his melee defence won’t be so exaggeratedly high, but his ranged defence will be higher and he’ll even be able to form shieldwalls to bolster both. But he needn’t be a swordmaster – he could be a dagger-master or a mace-master …
I tried it with one of my melees, and i got like +3 melee defense. Not worth the perk.
It might be worth on a max level guy with +3 talent on melee defense who has taken melee def on every level up.