So, that person on the WoK cover is just supposed to be a generic Sharbearer, according to the artist. However, it does match another Sharblade we know of exactly. I don't know how far you are in the series, so I'll spoiler this for WoR all, maybe early OB:
Even though it matches that Blade, since the artist says it was meant to be a generic Shardbearer, I wouldn't read much into it.
Eshonai's Blade looks like this in the official Call to Adventure art:
Chiberty's post in Can anyone design me the Shardblade from the front cover of WoK? was marked as the answer