Well, I don't have a HM sin but I suppose a str build would be better than luck for 1-15 because even HMs dont get enough skillpoints for luck to be efficient. Maybe a stronger version of the 3str/2dex build would be better (maybe 5str/2dex?). I think you should put 2 dex instead of none because evasion will be higher, you'll have more sp, and still have high damage. You could lapis for str if you want higher damage or hp/rec if you want to be a little more resilient.
I found the combo Fatal Hit>Halt Kick>Stun Crash>Tetanus>Aggravation to be very effective as it subdues the enemy and can usually kill any squishie in one use (especially if youre HM). And if you crit on Aggravation, game over for them.
That's a sexy reply. o_O
I use the same combo as you, afflicted. It works very well in PvE, and I haven't yet tested it in PvP but that will come soon.
I agree with afflicted, though. A more powerful build for assassins work better when you're still putting in points for dexterity. In my opinion, if you want to still put points into luck do it, but do it every so often. Maybe every 2-3 levels and only put maybe 1 point - 2 at the most. I don't really do luck that often, for me it's about every 5 levels and only 1-2 points.
It's all about playing a build that you're comfortable with.