[1.7.4] Alchemist golem has weapon in its Miscellaneous inventory tab

[ScienceBall]

One of the weapons in my alchemist golem's inventory was in the "Miscellaneous" section, unlike all the others in the "All kinds of weapons" section. It had a "Move to normal inventory" option, which moved it to the "All kinds of weapons" section, but I wonder how the weapon ended up in the "Miscellaneous" section in the first place.

I can upload a screenshot, but I doubt if that would help much.