I'm a Bard L5. At L4 I asked Xanos to join me and instructed him to only level up as a Barbarian. At that stage he was 2 Sorceror 2 Barb. When I reached L5 I saw he was 2 Sorceror 3 Barb, but his strength was still 13.

It looks like I will have to relevel him to get rid of that extra level of Sorceror and put his ability point into strength. Do I reduce my own experience to L1, instruct him to level only as Barb, then level up again?

EDIT: I reduced my toon's XP, but it had no effect on Xanos. I tried to reduce Xanos' XP using the cheat for my toon, but that also did not do anything. So I'll make the best of things :)

It really doesn't matter.

I checked. Xanos starts with 12 Str.

So with 13 Str, he has already allocated his 4th level attribute point to Str.

Even if you could re-level him it would change nothing.