A Mandalorian(Don't care if it's Boba Fett.) would 'kick Exar's shebs'? arguably the third most powerful Dark Lord of the Sith ever? one of the finest duellists ever? the guy who put Luke Skywalker in a coma, as a spirit no less? I can't see that logic.
Yes, but just because one's a fine duelist doesn't mean they could stand up in, say, a bare-knuckles brawl, or a fleet-on-fleet battle. Mandalore was a brilliant tactician in addition to a beast in a brawl - and Exar always reliant on his lightsaber in a fight, and he was a fighter, not tactician.