to Draco_Lich: thank you.

You're welcome. :)

But how did you manage, since the spell is only in Verkhovin's diary?

I decided to earn some extra money and sailed to the ruins. :) You can take quests for money and experience. For example, I'm leveling up a priest, but I want to earn the Amulet of the Green Man or (what a noble goal!) save Frosgard. Then I go to the NPC who initiates you into the druids and ask for a quest. If it's available (if I have a healer who hasn't been leveled up to a priest yet), a list of candidates will appear. But since I need to become a priest, I just click "OK" without choosing anyone.
The same goes for the lich. The scholar takes both quests.

No. I got all the artifacts in the dragon cave. Instead of killing him, I ran to the chest, grabbed the artifact, and ran out of the cave. And I did that until I got them all, I just can't find the singing sword:(

That's what they are. :) There are also some in the training hall.
You don't have to do it on foot – you can place Lloyd's beacon in front of the cave – GM, I think, of the Element or Spirit – I don't remember, maybe it can be read in the presence of monsters (I think a weak one could read it, and the priest had an infinite "divine intervention"). And then you clear the chests (there are two of them) and leave.
When the chests stopped upgrading, they told me that I probably left on foot. :(
What sword? And I didn't manage to fully equip the lich (there's a set of artifacts there that are only available to scholars and liches). :(