But if we came across an old battleground or a failed raid and there were arrows in the corpses, it would be neat to retrieve them and add them to our characters. Also, if there were wounded that were arrow shot, we had the ability to remove the arrow and heal them. Just for those personality or fame points.
Fire and frost effects that stay, like a duration fire spell. Keep the flaming, well, flaming until cindered. Shatter frost would be interesting. Freeze an opponent or creature and then hit them with a sword or mace to shatter the pieces.
The deer hunting in Oblivion was nicely done, and many times I thought I was playing one of those Cabela sports games. Just make it so that we can harvest the skin and antlers too, instead of just the venison.
I like your ideas. As for the arrow thing, it could make role-playing a healer, paladin, or saint better, since that would make actually healing people possible.