Re: RUINED BLADE quest bug from DRAGON AGE INQUISION BASE GAME.

This is why you should always keep multiple save files, including one at the start of dungeons. 😉 
Does it really count as a bug if you left the dungeon after summoning the creature and came back? I've never done anything like that before, so I don't know... I know loot disappears if you leave an area, is it surprising if specially triggered enemies do, too?
There are far better 2H weapons in the game, including those you can craft. 🙂 (Think you can get the schematic for this weapon from the Black Emporium). As far as I'm aware, Bioware has no plans to create more content for the game, including patches, so other than reloading an earlier save, there's not much that can be done. Unless someone else has had this problem and found a way around it.