Call it whatever you want but make it like Shuriken Expertise. Make it use the your highest stat modifier for the extra throw chance though rather than just dex. Also make it exclusive with Shuriken Expertise. The reason is that right now throwers are exceptionally terrible. Not a little terrible, EXCEPTIONALLY terrible. The best non-shuriken build is probably a vistani bard but it's not even half of a shuriken build (1/4 maybe?) and shuriken builds aren't even that great themselves.
If this weapon viability issue had a melee equivalent it would be like scimitar doing 4x as much dps as a rapier and only 1 class gets full use of scimitar with one other class getting half use.
Also wouldn't mind seeing Fate (raid throwing dagger) get a monstrous buff. The random on hit elemental damage needs to be multiplied by 10 or so. I never did understand why the shuriken was given OP properties on the already best throwing class while the dagger is as MEH as MEH can be on a already terrible platform.