So this materia could only be made from -- and attached to -- certain job-specific gear?
As much as I like the general concept, I see a couple of issues with this idea:
- Job materia being a closed-system is somewhat contrary to the vision of materia being a broad customization platform.
- Ability Enhancements (eg. Reducing Jump Recast) could be very difficult to balance, esp in regards to forbidden melding.
The second issue is obviously the biggest one. If "Jump Materia IV" only drops the jump recast by 2 sec, people will pass it over for better materia. However, if it drops jump recast by 10 sec, then a 3-melded lance equals a 30sec reduction in the jump timer, which might considered overpowered.
I suppose it's workable, but there's a fine line between useless and broken.
Another option is to make the Job materia lock out all further melding. That would make things easier for balancing and force players to really make tough decisions on when and how to use it -- but that also is making exceptions to the rules of the current materia system.
For my part, I'd be fine if they just keep the bonuses on the Job-specific gear itself.