What I found weird is that any cleric needs to have a deity, so the fact that the spell rewards casting it (by succeeding) without a deity nor deity's weapon to invoke seems odd. and while it isn't unreasonable that a deity-less character could use UMD - what deity are they invoking?
Cleric wrote: Deity Selection
Due to being set in the Forgotten Realms, all divine spell-casters in the Original Campaign of NWN2 are required to select a deity during character creation. Clerics choose an alignment and race first and then receive a list of deities appropriate for them to choose from. The list of domains for each god can be found here.
Spiritual Weapon wrote: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. The default weapons associated with each alignment are as follows:
Chaos: Battleaxe
Evil: Light flail
Good: Warhammer
Law: Longsword
