So to put it simply I upgraded the Arctic Horn Bow (the low level Amazon Set bow) to the exceptional version of the bow which it is now classified as a Rune Bow, I have all the stats required to equip the bow and I am the required level and it will not let me equip the bow.
I have upgraded the chest armor and the belt to the exceptional levels and they allow me to equip them just fine, the bow however will not equip.