Arthas stats?

So opening the maps, I noticed that Arthas with Frostmourne has some strange stats.

If you play on normal, when claiming Frostmourne, he will get a chaos attack, along with 12 bonus damage, 2 to all stats and 50 extra base hit points.
Now if you play on insane, he'll retain a hero attack, along with 22 bonus damage and no stats.
I would understand this if the difference were huge between the two attacks, but the only difference is that Hero attack does reduced damage to Fortified. Other than that, they're identical.

On the next map, Isolation, his stats are once again different.
He has a Hero attack, 10 bonus damage and no stats at all.

So, what's going on?

The bonuses obviously vary with the Chapters and difficulty.

Don't be amazed by the 22 damage bonus, chaos attack + 11 damage alone are way better than it. Plus, don't underestimate the power of +2 stats and +50 hp, that's 100 more health and an extra 45 seconds of invulnerability.

I remember removing his Chaos attack for insane mode, but not adding the extra damage.

If I did that, then it was probably not intentional.

No, you never added the extra damage, Blizzard did.
You lowered that extra damage from 22 to 12 for normal Arthas, but not for insane Arthas.

@Lich: The main concern is the damage, the stats can stay.
Hero attack does full damage to everything, expect for Fortified (=buildings) and Divine (=Does not appear on this map.). Chaos attack does full damage to everything.
Insane Arthas is now a bit better at dealing with enemy troops, which obviously makes it easier for you. By the time you get to demolish structures, you will have Steam Tanks.

I think I meant to reduce the damage on the insane arthas, doh!

Also, removing Chaos damage makes it pretty hard to him to solo the base on the right at the start

Yeah, that's clear and I agree with that change.

Ok, I'm gonna treat this as a bug rather than a suggestion xP
So this is now resolved & closed!

The new stats:

Frostmourne Arthas:
Chaos Attack
+22dmg
+50health
+2 all stats

Insane Frostmourne Arthas:
Hero Attack
+10dmg

Custom Chapter Arthas:
Hero Attack
+10dmg