I took non-runic gm boomerang and imbued it with the following properties:
Fastcast
Mage Weapon ( -20 Magery )
50 Hit Lower Defence
Then i used the mysticism spell "Enchant" which adds spellchannel and 50 hitspell to the weapon.
The boomerang would swing @ targets but it would never hit.
So it would seem "enchant" spell is not working with the "mage weapon" property.