I have seen over my years of playing Pirate101 that trying to stitch something with say the duck of deaths weapon with like a eagle gun or something and you cant do this because one of them has a grant and one doesn't. I don't see why we cant stitch because of this because there would be no effect on stitching whatsoever if you stitched say the nefarious novablaster with the snow blasters (what I was trying to stitch recently). So KI, why is this so? I don't think there is any problem with stitching an item with a grant with an item without one.
This has bugged me a lot too. For whatever reason, stitching is very complex and rigid. A and A go together, B and B go together, but B+ and B do not. Either way, I'm sure Kingsisle understands how restricted stitching can be, especially on the topic of the Nefarious weapons.