Matt's shots missed the servomech by a narrow margin. Viggo, however, had far less luck - his weapon, whether due to a construction fault, a cartridge fault, or simply poor maintenance or jam-clearing, suffered a critical malfunction. Put simply, it blew up in his hand. Viggo's armour managed to intercept the flying pieces of metal, and he was left holding the handle with a few leftover twisted pieces hanging off it, but the weapon itself was pretty much beyond recovery.
And the servomech was still functional.