From the description of spiritual weapon:
"The weapon that you get is often a force replica of your deity's own personal weapon. A cleric without a deity gets a weapon based on his alignment. A neutral cleric without a deity can create a spiritual weapon of any alignment, provided he is acting at least generally in accord with that alignment at the time."
So, I am playing a cleric of Sarenrae, found a wand of spiritual weapon created by a cleric of Rovagug, what is the form and the alignment of the weapon when my character uses the wand?