Where is DK sword in inventory

[Iscah]

Actually, no. The intial level 30 weapons for DRK, MCH, and AST are not craftable and do not have a HQ version.

I had to check because that sounds strange. You need to be able to get a new one if you discarded it before you could equip anything else, or you're stuck.

It seems you can't craft it (very odd) but you can buy it from NPC weapon shops in the starter cities and Ishgard, and also from the merchant at the Forgotten Knight who sells DRK weapons. The AST/MCH equivalents would be available from the guild merchants.