Normally weasel is a client side error code. Unless it's impacting a vast majority of players then Bungie will investigate the issue. Mentors won't know anymore information then what Bungie tells us.
Yes i agreed Normally Weasel is client side but this issue isn't.
Read my post: https://www.bungie.net/en/Forums/Post/262323470?sort=0&page=0
I can confirm its something to do with account on Bungie side. It happen since Hotfix 6.3.0.5 when it messed up with players data that cause losing progress, triumphs and seals. Rollback seem not really fix those issue as a whole.