Medieval Sloping Desk?

I have a friend who is writing a medieval story. In the story, a struggle happens in a scriptorium. One of the people grabs an item as a weapon. However, my friend is unsure if such an item exists or its name. The item in question is the triangular object in this image that scribe is writing on. It appears to be separate from the table, but my friend is unsure if that was the norm. Also, does anyone know what that triangular object was called? Currently, he has sloping desk as a placeholder, the result of an internet search for scribe tools, but would like to know the actual name, if any. (Portable sloping desk?) Thank you for any help.

A writing slope. An unusually steep one.

I would call it a lectern, though it’s a weird one.

“Writing slope” is what I’d call it too, and they do seem to be pretty common in period illuminations. I wouldn hesitate to call it “the norm”, though - full desks seem just as common. Look up google image searches for “medieval scribe” or “St Jerome in his study” for a idea of how common they were relative to desks or pedestals.

You write on a slope with a quill because that allows the quill to stay level, if you write on a flat surface the quill must point downwards and gravity pulls excessive amounts of ink onto the vellum. So yes, unusually steep writing slope.