The problem is the difference between Elyos and Asmodian Assassins in the game of Aion. We prefer the look of Asmodians. But the Elyos get a major advantage with the level 45 stigma skills. Elyos get a skill that silences the target and slows attack speed. Asmodians get a skill that heals you for a portion of the damage the skill does.It's a level(cheap aion kinah) 50 none stigma skill, not 45. In general, they're not a lot different, but elyos 41 skill is better than asmodian.
The level 50 stigma skill your talking about is going to be a rare used skill. Not every assassin will be using it and you probably wont find many that will be. Though the Elyos skill is great it's mostlikely a very rare drop. As far as if it will make a difference endgame, the elyos would be nice against casters but with godstones that can do the same effect you wont need the skill and will see the effect a lot more using the godstones.
It's actually two identical skills: There's a 45 stigma, and a 50 non-stigma. They share a cooldown, to the stigma one is pretty much useless.After double checking armor, it appears, according to them, that there are *3* identical skills: a 45 stigma, a 50 stigma, and a 50 non-stigma.
Also, we think the asmo level(aion powerleveling) 41 skill (+100% physical attack, at the expense of evasion and magic resist) is more useful than the "Second Aethertwisting". The asmo one will help burst someone down during a stunlock chain. We feel like the elyos one is more situational (and they're both 10m cooldowns).