WARNING: I am a player. Please don't spoil this for me.
So we're just about at the end of the Sword of Valor and we've recovered this +2 transformative glaive called Soulshatter. Now, I'm the party 2H guy and I've been using the ranseur of the gargoyle up until this point, so the party tossed the weapon my way. I was able to identify that the weapon cast summon monster on my own, so I know this thing is magic. When the party diviner identified it, though, he couldn't detect anything evil about Soulshatter.
When I tried to store the weapon in my efficient quiver (I had given my ranseur demon bane, which was more useful thus far than a simple +2), it exerted its ego upon me and forced me to wield it for the day. On top of that, I'm pretty concerned that this weapon didn't radiate any sort of alignment aura at all when we tried to identify it with detect magic. I'm pretty sure that its supposed to do that if its intelligent. Then there's the fact that it willingly aided a Chaotic Evil antipaladin in combat and that we know that there's a Corruption Forge under Drezen Keep (we captured the traitor's cousin alive and interrogated him before going down into the depths of the keep). All of the notes we got from the dwarf's cache indicated that he's been using this forge to create evil magic items, such as his armor.
As a result, my character and I are both convinced that this weapon is evil. The obvious answer based on the results we've been getting are that this weapon is somehow casting nondetection or something similar on itself, but there's just one problem: I'm the most magic-savvy character in our party and every other player thinks that I'm being irrationally paranoid! Because the mere concept that the intelligent weapon that was formerly wielded by a Chaotic Evil antipaladin could POSSIBLY be Chaotic Evil is apparently baffling to them. It's almost like they expect it to be a weapon that we can use!
I could use some help coming up with tactics to thwart this nondetection effect to prove to my allies that I'm not insane. Remember, please don't tell me if this weapon actually has nondetection or not; I don't want to know!
You could try dispel magic rendering the item temporarily none magical, then detect evil looking for the evil or lingering evil you suspect as hopefully the detect magic will prevent anything it could be doing to block you.
You could also dump it because it mind controlled you but that would not prove it evil.
Or hit an angel with it and see if it overcomes the DR
There are a lot of magical ways to fool detect alignment, it could theoretically be using any of them. The problem with no alignment is that the party probably only has detect evil , unless it also has no alignment for detect good, chaos and Law you have not ruled out it having an alignment and even then it could be true neutral
If the weapon is under the effect of a nondetection, shouldn't this be visible as an illusion aura under detect magic, which someone must have cast to identify the magic weapon? It won't thwart the spell, but it may help your character convince his or her companions that there's something fishy going on.
I would use a divination spell to know in it's safe to use alignment-wise. Dispel Magic also works, followed by quick detect evil
Our Oradin tried that. It registered as magical under his detect magic effect, but not evil. I'm Chaotic Good, so I suppose I'll know if this weapon is Evil if I suddenly have a negative level next week. >_>
Oradin = Oracle/Paladin?
Yes.
Short of divination, even an augury to ask 'will it be weal or woe to keep this weapon?' type question may give you a better handle on what to do.
The other spell that may work is commune, but I forget if that is lower or higher level than divination.