Understanding is indeed unicorn horn. Brilliance is made of arcanite.

Riiight, Arcanite. Which is a good thing because while gold will harden to diamond at around 40 INT, arcanite will harden to mithril at only 25 (30? god, it's been too long since I played IVAN), and can be further hardened to octiron.

Which would be nicer if a) mithril gave more than an extra 2 AV and b) octiron didn't require the same amount of Int to harden to (according to the wiki) as diamond does (and since diamond helmets give 6 more AV than the octiron helmets, generally speaking a more useful use of harden material). A scroll of change material and the right amount of Int will make all that a moot point o'course.

You're also forgetting the stat that is increased. A helm of brilliance +5 can become octiron 5 INT earlier than a helm of attractivity +5 (assuming you don't have both).

Here's my full set as I walked into Attnam. Luckily a pet took care of the skeletons carrying those axes, I'm sure I would have been one-shotted. They ended up being my weapons for quite a while.

It's a shame there aren't any axe artifacts in vanilla IVAN.

Is that a screenshot from 0.50 though? The default weapon for a skeleton is a bronze axe -2 (with slight variations). Those enchantments are almost preposterous.

Can be. Later in the game it's the same as in the case of veteran dark knights in +9 iron armor.

Yes, it is regular 0.50. My only guess as to why they were enchanted so high, is because I had a pack of wolves following me from a fountain and an angel... I didn't have Atavus's armor yet. Actually, I don't think I had any body armor at all.