There isn't any mention of a mech he pilots in the books. Looking at the NAIS 4th Succession War Military Atlas (Vol. 1, p. 113), it shows the TO&E of Team Banzai, which are all Elite/Veteran pilots in either Assault or Light mechs. The Command Lance of the Regimental Battlegroup is an A3 for House Davion, which would consist of a Marauder, Awesome, Orion, and Warhammer. I would lean towards the Awesome myself, specifically the AWS-8Q mentioned earlier as that seems his style.