What was the name of Uther Pendragon's sword?

After some reading, that particular sword doesn't appear to have a name. All the names given and their variants, were for the sword given by the lady of the lake - which was of course Excalibur.

Variants include names like Caledfwlch, Calabrum, Callibourc, Chalabrun, and Calabrun with alternate spellings such as Chalabrum, Calibore, Callibor, Caliborne, Calliborc, and Escaliborc.

However there is a parallel tale from Norse mythology, whereby a sword was drawn from a tree and that was named Gram.

A snippet from the link as follows:

"The story of the Sword in the Stone has an analogue in some versions of the story of Sigurd, whose father, Sigmund, draws the sword Gram out of the tree Barnstokkr where it is embedded by the Norse god Odin.) In this account, the act could not be performed except by the true king"

Some remakes of the tale made it clear the same sword drawn from the stone was the one given back by the lady in the lake, but it seems that is not correct.

I always thought it was the very same sword as Excalibur, so thanks for asking this question. It's always good to learn something new.

Excaliber..................

Caliburn