How can you make him from existing Perry miniatures .
Well what have we got to start with ?
A mounted abbot, a bishop on foot and a variety of heads from different figures.
Apparently Adhemar did fight/ aligned himself in battle and at one stage carried the "holy lance" into battle.
This is not a contemporary illustration but it does show the bishop carrying the "holy lance",another near contemporary illustration below shows the Bishop on his death bed with almost identical headgear.
Other references to use could be Bishop Odo in the bayuex tapestry , this might give us an idea of what a bishop would look like in a war zone.
Nearly completed this conversion of a Norman command figure, given him a one piece spangelhelm with some gold around nose piece. I have not decided who I want him to be yet , but he will be a high status knight.
I have just given him a generic dragon shield until I decide.