How about coupling it to skill? Speed and distance like this would also make sense for arrows. Or:
Spells:
Increased complexity of the spell also slows it down. So a low level fireball when you're high level would be very fast, but not the uberball.
Arrows:
Lightweight arrows travels fast and long at high levels, but are weak against armor. Daedric doesn't go that far but is more effective.
Dunno, just thinking out loud...