By virtue of being an official albeit not positively canonical product, the game expansion and the 'Mechs presented therein including this one must be considered apocryphal.
The Belial is a ballistic-focused version of the Uziel medium 'Mech, not suffering as badly from overheating issues and carrying a pulse laser to back up the twin Gauss rifles it brings to the fight. It weighs in at 50 tons, and travels faster then any other medium BattleMech, with a max speed of 54 km/h.
In an unusual move going against the usual BattleTech universe standards, 'Mech speeds are expressed in mp/h rather than km/h; as such, the speed figure has been converted to km/h for this article.
- MechAssault: Phantom War user manual, p. 16, "Belial"