What it says on the tin. Playing the stoneblock modpack, which has more than enough mods for it to be something else's fault. Still, decided to make a note here that there is an issue.
Edit: After creating a new minecraft instance with only JEI and Randomthings, I found that the Spectre Key and Spectre Anchor are also missing from JEI in stoneblock. I am happy to debug this myself, I just need a little help with finding the tools to fix it.
Edit2: After Poking around for a while I found the swords ID, and was able to able to summon it via console commands. It still did not appear in JEI, and displayed no crafting recipe when clicked on.

Are you sure the Modpack Author didn't just remove it from JEI? If it only happens in the Stoneblock Modpack i doubt it has anything to do with Random Things.

It's disabled by pack author along with the key and some other RT things IIRC.

Huh. Weird. I'll go pester them about it then. Thanks!