I was thinking of the toughness versus ward save. I am not sure on that one. Perhaps there would be a situation that it would benefit you by making your lord tougher to throw wounds on.
I have had great success using my standard to benefit me in prolonged combat. I take the rune that allows me a +1 combat resolution and the rune that doubles my unit str. That is usually good for another point of combat res. It has saved my bacon in a situation where my opponent knew I was outnumbered to me getting a draw in CC.
I have used the rune that lets me take a leadership roll on 1d6 before and it is nice. The double unit str allows you to have staying power though. My longbeards almost always carry the +1 combat and double unit str. It has helped a lot. I was thinking of trying the one that makes the unit cause fear. That would knock your oponnent off kilter for sure.