Hypersmurf said:
Axiomatic and Anarchic
are incompatible, because an Axiomatic weapon is lawfully-aligned, and an Anarchic weapon is chaotically-aligned, and you can't be Lawful Chaotic Neutral
Actually, Hypersmurf there is nothing that prevents the combination of a Chaotic/Lawful (I hate the Axiomatic/Anarchic terms, just a way to confuse poor half-orc barabarians. "Hey! Krusk wadda you want the Axiomatic Great-Axe or the Anarchic Greatsword?" Krusk- UHHHH, which one of those makes Krusk wimpy again?" Anyway nothing game-rules way prevents a Holy/Unholy weapon.
I Know because I recently made a Druidic relic for my campaign world that was created to mark the Druid Wars where the various druid alignments (N, LN, CN, NG, NE) had fought amongst themselves for several years & afterwards created a powerful weapon whose purpose was to keep druids purpose into perspective. Basically I wanted an item only true N characters could wield. I ended up just making a Holy/Unholy/Chaotic/Lawful Scythe. Thus any Lawful, Good, Evil, or Chaotic person who wielded the weapon would gain at least 1 negative level. I made it an artifact to avoid game-creation mechanics, but it is possible.
Bascially a low-level Evil person with the Craft Magic Arms & Armor feat makes a +1 Unholy Mace. Many years later, this same person has changed his alignment to good may then enchant his mace with the holy property (though he gains 1 negative level then entire time he is enchanting his mace). Why he would do this is another matter altogether.
Thus, stricly by the game rules, holy/unholy items can exist. From a game -workd stand-point they would be extremly rare, almso non-existant. Still I think it might be fun to let the party find a sentient lawful, chaotic weapon.