|Dr. Johnny Fever|
They do stack. One is an enhancement bonus on the weapon, the other is an enhancement bonus on your attack rolls.
Similar to how a Barbarian can benefit from both Rage and Bless (despite them both being morale bonuses).
Probably dragging this thread off-topic, but I don't think your reasoning is correct. Both the blessing bonus and a magic weapon bonus are enhancement type to attack rolls; I don't believe that they stack.
A morale bonus to attack rolls is different than a morale bonus to strength which results in an increase to attack rolls, that's why they work together in your rage example. I wish the blessing DID stack with a magic weapon (I have a ranger with the strength blessing from the divine tracker archetype) but I really don't think they do.