You are spending more time focusing on what to do with your hands, to even attempt to learn the nuances of metabolic slowing!

Is it weird to answer a question from 6 years ago?

No this is the echo when you get a skill improvement prog while you're a ghost. Just so you can't abuse your invulnerability, pass door, flight and free recall (e.g. teleport spam).

What happened was that your transmuter got a spell % improvement to metabolic slowing per RNG, but you lost the improvement due to wielding a weapon you don't know (in this case, hands). A low level transmuter with no hand to hand skill yet should not try to practice skills/spells barehanded in order to get skill/spell improvements.

Basically, you have to wield a weapon you know in order to improve skills. You haven't practiced hand to hand, thus since you aren't wielding a weapon you know (hands) you can't learn.