Weapons from the merchant elf in the ARKS and its strange properties (Divinity: Original Sin 2)

Good day.
Strange question, but yesterday I encountered a problem.
There are ARKS merchant, sells an unusual weapon, play party online, I bought a tank one-handed sword seeking truth he is a divine class, gives good stats, but he has one drawback, it imposes on the owner of the blind on a permanent basis, but gives 100% accurate esti a way to relieve curse?

Just got a few more things but not that cruel.
The imbalanced staff three sisters with 3 additional spells and a good bonus the battle, while minuses has not found.

Also have dvorecna axe divine spark, beats MAG. the damage gives constant spark but imposes on the media set fire to the blood and + 20% to fire.

Who faced and figured out how to equalize the cons, please give advice.