Well I would say that the significance of this pencil is exactly the same significance of any other pencil. Interesting nuances and unusual features were discussed here:
https://www.reddit.com/r/mechanicalpencils/comments/y1m9e8/2_mm_goatthe_b_teams/
As to its rarity — I think the absence of any info or that you never actually see one in millions of listings speaks for itself.