>>719147627
Thalorien was never a Death Knight. You're thinking of Koltira.
That sword is Quel'delar, a Dragonblade that was given to the High Elves. It's supposed to be used always and only to protect Quel'thalas and Thalorien died using it to protect his unit's retreat to the Sunwell.
When they remade WC3 they made him a new model to use for the Siege of Quelthalas and had planned for him to have a story presence and then they dropped almost everything they were going to do with Reforged.