The reason we gave runeguards the runic wards in the first place was to make them not pointlessly vulnerable to the dwarf's own crossbows. If they go back to the basic shield type they once again become only modestly shielded infantry that deals excessively poorly with crossbows. Please don't
Still don't really like slayers as summons... but if they absolutely have to be, it had better be a gem type that the dwarfs get a very nice income of.
Edit: Okay, so really the runeguards were given runic wards to make them more interesting as sacreds. I guess we'll see if they are still worth using without the runic ward. I am somewhat skeptical, but I'm willing to be proven wrong.