Hunters are special thats why you cannot use your spell reflect on us :-) (hehe a good start for a post isn't it?)
Our ranged attacks are no casts, thus a warrior will not be able to reflect them.
However some ranged attacks (or shots if you like that term better) have some cast like behaviour.
Auto-Shot pretty much works as Auto-Attack works for melee classes (except that it can be delayed by any other shot which is not the case with melee autoattacks which are not delayed by specials).
All ranged attacks which have a cast time (steady shot, aimed shot, multi shot) can be interrupted as a mage's spell can be interrupted.
Just because special shots cost mana and have a "cast time" does not mean they are casts which can or should be affected by spell reflect. Basically it is an arrow/bullet flying towards the opponent.
An arcane shot can be imagined as a bullet/arrow imbued with arcane energy which is fired at the opponent. As the damage type is arcane, armor will be useless, but the damage can be resisted (and will be resisted heavily on opponents which have a higher level of arcane resistance).
So suck it up OP, there are some abilities which are neither mitigated with armor, nor reflectable with spell reflect (although you still can beat a hunter in a PvP scenario, not wasting 30 rage on reflecting an arcane shot might help in that situation. You'll need your rage to hamstring and charge the hunter and of course to do damage to him).
On a sidenote. Traps are another thing doing non-physical damage and those cannot be reflected either. This of course is because the warrior goes into a trap, his shield will be of no use to "reflect" the damage back upon the hunter who lay the trap (although I imagine it would be funny to see a warrior throwing back half a dozen snakes with his shield in the direction of a surprised hunter).