Yeah I meant the portal. I have a feeling it could be the 'Drowned Pass' becaue I never found Vulgrim there but I have done a LOT of backtracking and couldnt find the location with the lat sword piece.
If its on one of the locations that are the smalles sections of the world map you they are all connected to samels location. So you would go up, left or right from the middle section toward the location icon. and fallow the tunnels till you get there
it's the drowned pass, when you reach the entrance after the giant fan, follow the path on the left hand and not too far down you will see a path branching off to the right. and yeah the blade fragment is there.