Let's just allow enchantment stacking. Keep layering on the +10 damage effects to the arrows until you are a GOD.
[/sarcasm]
I say it should go one way or the other: enchanted arrows or enchanted bows...not counting scripted arrows like the Sanguine Rose from Oblivion's DB quest. Both is overpowered. Just as if you could enchant your socks, underwear, pants, belt, shirt, second shirt, sweater, neck warmer, wristwatch, tattoo, hair, and armor; it just cannot be balanced.
Hey, tattoos. That would be pretty cool; you pay to get a permanent tattoo that bestows some magic bonus.
if thats your argument, then they should remove dual wielding or restrict it to 1 working enchant at a time. Daggers attack extremely fast as it is, and stack on (even minor) damage enchants it can build up fast. Actually, that might be the way I go. Sneak in and see if I can get a double sneak attack in on my first move, then rip them apart.
Edit: Sorry if I come off as aggressive on that, not meaning to be but it sounds like it is, even to me