They used stone-headed clubs, as well as disk-(and pear-)shaped maces, but if you're wanting a bludgeoning-type weapon (even if it's not used as such), I think the main Egyptian weapon that comes to mind for me is a 3-headed threshing-type flail, e.g. the Pharaoh's crozius-and-flail: http://www.touregypt.net/featurestor...sandflails.htm
Alternatively, maybe something like a WFB Tomb Kings triple-headed chained flail-of-skulls? (e.g. could use animal skulls like the TK Ushabti have, such as cold one/lizardmen heads, painted up in bone colours)?
Excellent work so far on this!