According to Magic weapon special abilities, a weapon requires at least a +1 enhancement bonus.
Does this mean a good domain cleric's 8th level ability, or any other ability that bestows a magic weapon ability, require a +1 enhancement bonus weapon? Or does the ability bestow a +1 enhancement bonus? How would it affect an improvised weapon?
When the rules describe a specific ability, that specific ability may override a general rule. So when a creature possessing the Good domain employs the supernatural ability holy lance, he really does "give a weapon [he] touch[es] the holy special weapon quality for a number of rounds equal to 1/2 [his] cleric level," ignoring the usual restriction that a weapon needs to possess at least a +1 magical enhancement bonus before the weapon can have weapon special abilities.
For much the same reason that, for example, a creature possessing the feat Power Attack specifically can deal extra damage despite the game having general rules for dealing damage, a creature that employs the supernatural ability holy lance really can touch any ol' weapon and grant that weapon the weapon special ability holy.
(An improvised weapon isn't usually crafted to be a weapon but is, instead, just another object used as a weapon, so that object's not, technically, a weapon, and that makes the object an invalid target for the supernatural ability holy lance—but since that sounds really close to gibberish to me, too, this GM would totally allow a level 8 cleric to bash somebody with a holy pool cue or frying pan or whatever, rules be damned.)
Anyway, special abilities often let a creature do things the rules say the creature normally can't. The game makes many general rules then breaks them with specific rules. So a weapon that's the subject of the supernatural ability holy lance gains the weapon special ability holy, masterwork or not, magical enhancement bonus or not, but such a weapon gains nothing else from the supernatural ability holy lance except what the lance ability says the weapon gains (e.g. no free +1 magical enhancement bonus).
(To confirm what is, essentially, my gut feeling, I did some research on this topic, and a similar question was asked about the inquistor's bane on the Paizo message boards in 2013, and that concern dismissed. Otherwise, the topic's unaddressed and seems to be played as described above.)
Note that a GM that nonetheless rules that the supernatural ability holy lance can only be used on weapons possessing at least a +1 magical enhancement bonus likewise limits a fairly large number of similar effects (the sorcerer bloodlines boreal's spell-like ability cold steel and stormborn's spell-like ability thunderstaff, the spell flames of the faithful, and the inquisitor's supernatural ability bane to name but a few). Were I playing a character with such an ability and such a ruling were made, such a ruling would be insufficient for me to leave the campaign, but I would appreciate it if the GM provided me the opportunity to make different choices for my character. Such effects will often be useless to characters level 5 and below, so under that ruling campaigns will end—and characters will die—before such effects can ever be used.
No.
This is because the spell or ability which does this, simply adds the property. When it is a weapon property, such as holy, the weapon needs to be magical in the first place for the ability to get added. Why the weapon needs to be magical I have no idea.
This also comes down to the fact that none of the spells or abilities talk about adding the +1 enhancement bonus if it does not already exist or as a requirement for the casting.
This depends on the SOURCE of the Special Ability (SA).
IF the Source of the SA is the Player, then it can be applied to anything being used as a weapon.
(For example: Sampson and his weapon, a Jawbone)
However, if the Source of the SA is the Weapon\Item, then it MUST be +1 magical item.
As a Cleric, you will enhance the items with YOUR domain abilities, leaving the item as it was before once the effect wears off.
(Note: This does NOT give the item a +1 bonus unless otherwise stated in the SA)
Masterwork means the item is of exceptional quality and it can be permanently imbued with an SA or magical property.
Mundane means the item is of normal quality and attempting to permanently imbue it with any SA or magical property will destroy the item in the process.
