While looking for a source I found this Reddit thread, which is dated a couple of days earlier than the source tweet: https://www.reddit.com/r/Queensblade/comments/18dd83l/crimson_skilled_master_alleyne/
The Reddit poster has a similar username to the Twitter poster, and seemingly is the same person.

The Reddit image is similar but not identical. The two images are cropped differently: the Reddit image extends further to the left but the foot is cut off. Despite that, both are exactly 4096 pixels high, which probably means both have been resized to that vertical height, probably upwards given the overall blurriness.

The light particles, some of the leaves and parts of her hair are positioned differently between the two versions, suggesting that this is a screen cap of a simple animation.