The Ork head holding Steel Legion Sergeant seems rather a naff mini then. So off with his head, actually Ork head arm and transplant a pistol holding arm. Choose your flavour of pistol, laspistol, boltpistol, plasma pistol etc. Then you have a metal Sergeant mini with 2 pose-able arms. The spare pistol holding arm from the other Sergeant is the easiest to use. It comes with a locating lug. So the only conversion work is to drill a hole in the shoulder deep and wide enough to accommodate this lug. A bit of superglue and that's it.