Liches

Hi there,

I'd been playing Nethack for a while and wanted to try Slash'em for the excitement of all the new monsters and items etc.

So far I'm finding it much harder, which is a good thing!  One major problem I'm having, though, is Liches.  Nothing I do seems to touch them.  At the moment I've got a Valkyrie two weaponing a blessed Excalibur and a blessed silver sabre, and when i hit a Lich it just tells me that my attack didn't seem to harm the lich.  Meanwhile they're summoning all kinds of things and cursing my stuff.

Any tips?