As after digging into charlemange (since he'd hidden clarent) I found out that he'd wielded Joyeuse,
I found out that both Durendal and Curtana belonged to the apprentices of Charlemange.
Curtana was wielded by Ogier the Dane a paladin of Charlemange. (as i've read by edward the confessor to)
Durendal was wielded by Roland Also one of Charlemange's Paladins and was also used by Hector of troy.
Curtana also has an discription crafted in its blade.
[I]My name is Cortana, of the same steel and temper as Joyeuse and Durendal.[U]
And isn't it intresting that Charlemange at that time would have had 3 swords of power only missing the 4th one.
As tyrfing is called to be a cursed sword who brings death to his wielder that must be clarent.
Don't know if this has anything to do with the story though