Don't bother with Cure either, cross-classing at low rank and you find your Cure heal less than what mob can whack you for.
Cure/Sacrifice are definitely not as useful as they were pre 1.18, but telling someone to just not bother using it at all is bit insane.
Cure at the OP's current rank with an OK amount of mind(Even 20-25 or so) should be healing for 150-180 at least. There is absolutely no Leve mob that is hitting you for 180 damage a hit(Not counting WS's or Magic). If they are, you may as well stand there because you will never survive the fight.
The OP's biggest problem is getting destroyed due to not having a reliable way to recover HP(Speed Surge is 20-24hp a hit I think). As great as Second Wind is, you are going to take more damage than it will heal in a single fight. Cure is the perfect supplement to that, and with Lancer's naturally high MP(for whatever reason...) he should be **** near invincible with all that.
It's just weird to recommend Second Wind, which will heal about 200HP at OPs level, every 45 seconds, but say that Cure, healing 180~ HP every 5 seconds isn't worth bothering with. That makes no sense to me.
You are completely right about Stoneskin. It's probably not going to last past one hit from most things, and it may not even block that. I barely bothered to set it on my Conjurer(Just solo leves) as it didn't seem much better on the main class either. Just a waste of precious action points(Though if you have a spare 2 points you might as well put it on there)