I was about to make a thread about the same topic. Staff of Worms glitches out when using the arcanist skill Recuperative Treatise in the way OP has shown. Here is another sample:



In comparison, the other staff styles look the way they should:





Edit: The alignment of the staff effects is not even when comparing those three staves, even if the angle is not bugged. That's another thing that could be looked at: