Alright, Ive officially concluded there's something to this ^^
On my server... some crazy alchemy has been happening, (and not by me). This one guy got a +10 out of a 6Deg, NPC Euro shield, a +9 on a 60 Blade, and +11 on a 5Deg 1-handed euro sword. (This has all happened within the past week, might I add.)
Well... I noticed all of his items had 6x Lucky on them... ALL THE TIME.
So, I set out on a little test. Bought a cheap 6Deg sword, with 2 immortal, so if it failed I could try again, and bought 20 Luck 6 stones. Used 6 luck stones from the start, and kept it at lucky 6 times the entire time.
Well, it went from +0 to +8, without failing, then failed on +9. *Tries again*

why would you ever EVER EVER even contemplate wasting elixers trying to +9 a lvl 48 weap. especialy when you have an 8D char