What is the proper way to enchant a bow so that when you fire normal iron/steel arrows, they'll still do damage to Daedra?? I apparently enchanted mine the wrong way because Iron/Steel does not do any damage. I get the "your weapon has no effect" message every time I fire. This isn't to much of an issue, thankfully, because I carry a ton of enchanted arrows/throwing knives/etc, but sometimes I do run out and then I have to close into melee range ><

There is no way to do this unless you have a mod. The bow does not strike your target, so “cast on strike” does not apply to the arrows.

yes, major design flaw in my opinion.
out of curiousity, do you know some mods changing that?

In the vanilla game, placing ANY enchantment on the bow should circumvent the "immune to normal weapons" of Daedra and some undead. I do that all the time, often with a Soultrap 15 seconds, On Target, On Use (I named the bow "SoulFetcher", appropriately for a Dunmer archer. I've even used Night Eye, 5 points for 30 seconds, On Self, On Use, and took out Winged Twilights and other "immune" Daedra with it.

If you've got the MW Code Patch, I suspect there might be an option as to whether or not it affects them. If so, and you've got the box checked or unchecked, it's easy enough to rerun the setup and change it.

TrueRevan, I don't know of a mod that does this. I have loaded mods that put fletchers in the game that offer enchanted arrows (Balmora expansion). I think that you can buy unlimited glass arrows in Ald'Ruhn in the vanilla game, which can hit Daedra, etc.

oh yes, and the area effect arrows

well, what bugs me the most is the fact that magical arrows cannot be recovered at all from corpses (just another big design flaw).
that means, silver/glass arrows are preferable because you don't have to restock as much.
that's in fact how i played my last marksman character, silver arrows and a few nukes from the fletcher in vivec for the really bad guys (ascended sleepers).