Not much is known about Vandred, mostly because he exists as a name for an existing generic model in the 6th edition of the game. His blessings included four arms and a snake body, something he shares with Dechala. Due to his skill he was chosen to represent Slaanesh's forces in
ArchaosArchaon's army before he was killed by one of his subordinates and a fellow name for a generic model, Styrkaar of the Sortsvinaer. Styrkaar was made his replacement, and Vandred has become forgotten both in and out of universe. Vengeance would be his in a meta sense however, as Styrkaar was retconned along with the rest of Storm of Chaos. Sigvald replaced them both, even ending up with Vandred's "the Magnificent" title.
He's a generic model, he's whatever you make him.