Sword making also often includes Shinto rights of purification and in some cases an "empowerment/blessing" is imbedded in the sword during the process of its creation:
So, in that sense, sword blessing isn't the exclusive domain of Shinto. (Mikkyo and "sword magick" go way back!) And of course other cultures bless their swords and other weapons as well.
(I know you know that Doug, but I thought I'd mention it.)
As an aside: Which is the longer tradition I wonder: Swords into plowshares or Farm implements into weapons of war? History is depressingly predictable.