If I attached an arti rune to the Even Blade in Terentia's temple, would it reset to me?

Try it and find out!

Does a tierstone transcend all planes? Like if I was on prime, could I scry someone who's up on Astral? And does it work with aetherbubbles like the nexus worlds?

... Maybe I'm asking the wrong question. What is the most powerful scry tool?

It works one plane from the plane you are on. So if you are on Ethereal, it works for Prime, Ethereal and Elemental. Aetherbubbles (including Nexii) are completely separate planes, so do not work.

There is no "most powerful scry tool". It all depends on the situation. I think a mixture of demigod seek, a tierstone and a seeing stone would be enough for pretty much all situations, however.

It's established that the shard of a changeling is somehow different from that of the other mortal races, so you're not necessarily soulless if your outer shell is that of an illithoid. Maybe you are if your changeling shard is soulless, but then you're a soulless no matter what shape you take.

Can a tapestry be placed to cover a door going down? If not, is there an alternative such as a rug or carpet?

I wouldn't see why not. It's not like doors to the down are (necessarily) holes in the floor. They just go to a staircase that takes you down one level.

Tapestries can only be placed on compass directions, meaning no in, out, up or down.

But is there an alternative?

manse stake steak of concealment.

Then why am I not allowed to changeling to an Illithoid during village revolts?

Don't do that, I'm hungry.

I was reviewing my old inventory from forging and had a question.

I had a set of masterarmour which I can obviously not wear seeing as I am no longer a warrior or forger. Are my only choices for the set to either keep it as a memento or have it smelted?

Is it possible to sell to another warrior for their use?

to answer your questions:

yes, those are your only options

no, you cannot sell them

Considering that an artifact rune changes the ownership of an object and the craftsman as well - I assume this is so based on my MagiCrown prior to it becoming my MagiCrown - it might be possible to sell it IF the person is willing to have a rune on it, but then again, I don't remember there being a rune for armour so... maybe not.

In which case, can we actually transfer artifact crowns this way??

Does it change the craftsman? I runed my crown and it's still marked by Raflein.

Attaching a rune to a weapon changes the mark. Attaching a rune to jewelry does not change the mark.

Weapon runes didn't change my mark either. Are you referring to forging runes?

Another simple question: Does the skill level of an enchanter affect the quality of great robe enchantments?

No. I said attaching, as in artifact runes, not etching, as in forging runes made of coal.