To me it reads/sounds like this:

* You wear/use your weapons and armor. While doing so, each piece gains in these "afinity' points. When the points reach 100% you will have the option to <convert> the piece of equipment into a Materia. (Losing the gear > gaining a Materia) This can be done under the class that was using the gear.

* DoH crafters will be able to then <attach> these Materia to a piece of gear, adding whatever stats the Materia has to the gear. This requires a <catalyst> to preform the synth and always will have sucess.

* DoL gatherers will aquire the necessary catalysts for crafter to perform this synth.

* Crafters can also <remove> the Materia from a piece of gear (destroying the Materia in the process) and attach a different one.

THen lastly, the possibility of some forbidden technique with high failure rate to attach multiple materia to a item.