Mishka brought it up and I couldn't help myself.
The word was also used to derive several others mentioned in the Red Book of Westmarch. Tolkien was a philologist, you know. Taken from my trusty appendices:
Dwimmerlaik - n., in Rohan, necromancy or spectre; cf. ‘dwimmer-crafty’
Dwimorberg - place, Haunted Mountain
Dwimordene - place, Vale of Illusion, name in Rohan for Lórien
Anyway, more to the topic, I would love to see this word used in PS. Let's rehash the nature of mana.
In the basic GURPS ruleset, mana is also seen as something which is present in the environment, not something made or merely as a measure of magical strength. That's what has always made sense to me: the mage has some internal store of the stuff, which they draw from their surroundings, and when that is depleted it must be replenished. They only manipulate what they've accumulated.
Dwimmercraft (dweomercræft), then, would be the art of focusing, concentrating, and directing mana.
The words ‘magic’ or ‘mage’ originated with ancient arabic and persian thinking IIRC, and were used to simply describe practitioners in esoteric or occulted arts. The connotation of the supernatural or supra-physical came about during the Renaissance, perhaps?
Anyway, as to this Catyliasis stuff.
Midichlorians (mitochondria), anyone?
Perhaps mana exists in separate dimensions, and catyliasis — sorry but I must say that this word looks like straight gibberish — extends through both the dimensions of mana and the dimensions of Yliakum, and thus facilitates interaction. Only, that makes nonliving things invulnerable to mana. It makes more sense if catyliasis is what enables living things to focus and direct mana.
However, going back to dweomœr, it seems that glyphs and imbued nonliving things can indeed collect and accumulate mana: They can hold a charge, or act like capacitors for the stuff, or even channel it in the way that glyphs do, but they lack the energies necessary to do anything more.