So today I finally got crux of Crota but when I went to my quests it still says I need the crux to get a touch of malice should I delete my crux to see if this works. I Really want the touch of malice. Also What's thorn
ToM is a TTK quest weapon not TDB.
The Crux of Crota is to get a weapon called the Necrocasam which came out with The Dark Below.
For ToM please re-read what step you have to do.
Thorn is a year 1 primary weapon which can be obtained as a RNG drop from year 1 activities ( PoE/VoG/Crota) and if he sells it Primary Legacy Engrams from Xur.