[Rune Son of Bjarne]

I don't see the connection at all, I am afraid. There is just no hints at all to the swords being connected to the Kaaba, obviously we all make weird association when reading the books and sometimes drift of in our own thoughts. . . but it is very unlikely that all of these where the intend of Tolkien.

Anyways is it not quite common in european folk lore that special storries are attached to black rocks?

In Kalundborg fjord there lies a black rock and the legend tells that it got it colour when Valdemar the Young, the son of King Valdemar (II) the Victorious, was accedentaly killed by an arrow during a hunt.
(He died right at the rock and it turned black from grief or something of the sort)