It partially solved with cheating.
TLDR: Cheating worked with all itens except Cladhalíath
I'm going try to sum what I did I trying to restore Draining to my items:
1- First I checked if I had the draining.unity3d file. And I had it.
2- Then I exit the dungeon that I was at and went to a merchant. I sold my items (Cladhalíath, Borresaine and Edge of Reason) and bought it again - after I put it in a container and grabbed it and equip in a party member, dismiss him and recruit again. Nothing happend.
3- At this moment I thought that my "draining.unity3d" file was corrupted. Being so I download it again in the link suggested. And the draining still gone.
4- Then I decided it was time to cheat. I downloaded the IE mod and found the name of my Cladhalíath spear (that had a different name) and I added to my inventory. Oddly enough my recently added Cladhalíath had no draining.
5- After a really long time I had this idea: what if I tried with other items, because Cladhalíath had this ritual thing. And it worked with Borresaine and Edge of Reason.
I'm happy that I could save most of my items. But I'm annoyed because I lost a lot of time on this, I'm not in the mood to game anymore and lost my Cladhalíath - I really enjoyed that item.
Devs, if I may make a suggestion: in the next patch add a console command to add enchantments on items. I could save a lot of time for people with the same problem.
Ps. Draing lost the "Draing:" identification
So I guess that my lvl 13 party will be overpower in the WM. It will be better if I scale the game right? But if I do so, the game scale in the same lvl as my party or it scale to a pre determined value? o.O