If you watch the cutscenes where Vergil uses Beowulf, you can see that the gauntlets and the greaves glow. But when Dante uses them, they don't.
Why do you think is that? My guess is that Vergil is the "legit" owner of Beowulf, being the one who killed the beast, and the Devil Arm recognizes him as its master.
Why do you think is that? My guess is that Vergil is the "legit" owner of Beowulf, being the one who killed the beast, and the Devil Arm recognizes him as its master.