I am a bit confused as to what is with korlandril's left arm is about? Maybe I just can't focus correctly on the image, but is that a giant pincer?
Its a scorpions claw, meaning these are likely depictions of the three from the later portions of their respective books. From the way its being thrust forward, you can see the shuriken weapon on the top of the claw facing towards his helmet.
Do I just not remember this attachment / weapon of his?
Its been a bit since I read Path of the Warrior but I don't recall him using that when he got to that point.
I also personally always pictured the Eldar swords to be a bit more slender and thin, a more elvish styling and not so broad and ugly.
Keep in mind that the striking scorpion chainswords would likely be a bit more 'brutish' in order to allow the Eldar wielding them to have a stronger hit. And if you compare their chainsword with a howling banshees sword, the former is broader than the latter.
Thirianna is cool as shit looking,
Personally I'm not seeing it; in her book I don't ever recall any hint of an unwieldy looking staff and the pose is pretty dull.
zero hint of femininity,
Though I do agree with this, but I don't find that to be an issue of any kind as I imagine Eldar armour is not supposed to be terribly form fitting like some people try to make the likes of female marines and guard.
And I totally agree about Aradryan, just looks silly to me. The ranger look was way more badass and intimidating.
Again I agree, all I see here is some Dark Eldar corsair in a coat and with a rifle.