Now onto the fun things some concepts, in no particular order:
Witch Elves, with spears.

Coming straight from Clar Karond the city of beasts and the center of Anath Raema's Worship is the first suggestion, which in the lore exists, in all but name it's basically all done on Blackguards, in terms of rigging, animations, models, etc. Only thing that would require some tweaking is adding up the stats from 2 daggers into a 2h weapon, with fast attack speed value since this is meant to be a cosmetic variant.
Witch Elves, with swords



The good old favourite, which i should think needs no introduction and basically recycles DoK visual assets, in regards to the animations, models, etc. (Since DoKs are a lore abortion born from the Witch Elf theme there really is no reason to not give this option to Witches) (statless purely cosmetc suffices)
Disciples of Khaine, Blackguards and Witch Elves, with Draichs(Greatswords)



Now this suggestion takes us to Khainite Executioners, who are admittedly traditionally heavy plate wearing infantry(hence Blackgurard included in suggestion) and overall very thematic to both of our Khaine worshipping classes we know and love, in the DPS specs specifically. It would take form of an unique item for both WEs and DoKs, where the stats are added up, with the attack speed and parry added/subtracted accordingly. (for Blackguard it can just be statless and purely cosmetic) I will admit that this suggestion relies on the Dark Elves and High Elves sharing a skeleton rig, for their animations to borrow from their Swordmaster of Hoeth bretheren(who could get Glaives to be Phoenix Guard, if the logic holds)
Disciple of Khaine/Witch Elf Khainite Assassin garb

While stealthy Witch Elves are a huge departure from the lore it is what we've got so they may as well have the option to look the part, of their brothers and sisters, who indeed are very sneaky The Khainite Assassins. Now there are rumors of a certain Dev only cosmetic set, which basically does that, however this suggestion is more in regards to suggesting the Shadow Warrior head slot option of hood and mask. (statless purely cosmetic suffices)
Sorceresses, with offhand weapons.(dagger and sword)

It is very common, for Sorceresses of Ghrond to wield staff in one hand and sword or dagger, in another. Only downside of this i can see is Staff being classed as two handed, which i do not know how difficult it would be to plausibly adjust to allow for this cosmetic option. Alternative could be adding one of the cosmetic trinket positions into offhand place i suppose. But even the most significant Sorceress of the lore has Sword and Staff.
The sets, which allowed players to adopt the looks of other classes, which were removed also deserve a mention
Magus, with offhand sword

It technically is in the cinematic ;P (jokes aside It would be really cool)
I'd also like to give credit to SeanJeanquoi's amazing thread on Dark Elf and Beastmen troop concepts https://forums.totalwar.com/discussion/ ... -lord-pack. He has done some amazing research into the old, odd and the obscure Dark elf lore.
If you have ideas for customisation of even other races/classes like the aforementioned Phoenix Guard or perhaps spears for for Shadow Warriors post it, in the comments.