There must be a reason for no one ever weaponizing SS, perhaps its too unstable for combat on an archer or a longsword. I doubt a SS bomb accidentally going off would be very good for the fleet around it.

: We saw Longswords fly close enough to destroy large Covie vessels were the
: Longsword to have a ss drive in it.

That seems much more probable than as a missile, but based on the covie space superiority I don't think the UNSC had much success with fighter craft.

: It makes even more sense for anyone with Forerunner accurate ss tech to
: weaponise it

The Forerunners seem to be major fans of SS, so it wouldn't surprise me that they weaponized it. However, even they don't use SS as a weapon, instead they use Hardlight(the Forerunners second fave tech). I assume it's not very efficient or the whole slipspace galactic potential, something only Forerunners ever reached, makes it hard to be a reliable weapon. However, considering the UNSC is now the underdog to Cortana's Created conglomerate maybe they'll go back to using some improvised weapons.