An oft proposed house-rule is for shields to provide a 5+ save (or a 5+ against shooting or combat depending).
I'm planning on running a campaign at some point and it's probably the only house-rule I will make aside from armour cost.
It all seems fine an dandy, though I ran into one little snag:
I run Black Orcs.
This ruling would mean I have access to a 2+ save.
Everyone else of course has access to a 3+ save and I am paying the extra cost, but is this too much?