If I understand what you are writing, you are quite wrong …
Cursing uniques has the only scope of getting rid of an unwanted or duped unique and roll for a different (probably) one. It won’t get a “better” item, just a different one. Since all uniques are a bit different from each other, you surely have a slim chance of stats being a little bit better, but also to get 'em worse - and anyway big % are you’ll get a totally different unique anyway.
Instead, forging uniques using 5 star titans is the way to upgrade an unique to your current level, thus boosting his stats as if you had just got it.
Low level players should not curse their uniques at all unless they want a new different unique - and not to get a “better” one stat wise.