oh the one with his sword helding up? I know that one yes, I don't have it but I could help you. as Angularity suggested you could use wire for it. Buy a hobby drill (I bougth GW since I couldn't find a cheaper one, but you could find them in a hobby- or do-it-yourselfshop). If you buy GW you'll get 6 spare pieces for drilling of 1 mm thick each. you could buy smaller ones in the shops I just said (oh well, in the ones I visited you can) but the ones of 1 mm will be ok for the staff. once you got a drill, cut of the piece you want to replace, in this case the staff, once cut off, you drill a hole in the middle of the hand. If you've done that take some wire (a paperclip for example) and mesure it about the same length of the staff. Also cut of the staff's head and drill a hole in it too. Note: don't make the mistake as I did, drill through the weapon
once you got the wire off the right lengt, glue it inside the hole in the mini's hand and once you're happy with it let it dry so it can't move if you attach the head. If done correclty you'll normally have a nice new, unwavy staff. But I suggest to try it on some other minis first if you 've never used it before. I know what I'm talking about
just got my drill for like a week now Hope this helps, good luck with it!