
Originally Posted by
Quinn Inuit
Oh, I'm sorry, I thought you knew. All of those factions get imitation legionnaires already, triggered by the Marian Reforms.
Excessive scripting does reduce speed, but we're not too bad on that yet.
That kind of reform triggering would be awesome (imitation legionnaires, cataphracts...not sure what else, though), but I'm not sure how to script it.
I've had a look around, and following Aradan's hint, I looked at the Org's guide to EDB, and I found this.
http://forums.totalwar.org/vb/showthread.php?t=50439
Negative effects...
population_growth_bonus bonus -5 displayed the expected -2.5 in the building scroll but seemed not to affect the settlement population growth indicator on the settlement scroll. The same seems true for law_bonus and happiness_bonus. Religious_belief , however, does seem to work in the negative (this needs more testing). The general principle in actual terms is that a negative will only deduct from a positive; so a settlement with 15% law will drop to 0% law when a negative bonus of -20% is applied and not -5%.
Interestingly, giving negative bonuses to upgrades (in the format weapon_bladed bonus -1 for example) removes the unit with that weapon technology from being able to be recruited but is still listed as available in the relevant building scroll. A building that negates the negative bonus will restore the unit's availability for recruitment. Clued-up modders will see the potential for this feature 
The EDB lists the following available weapon types.
; weapon_bladed [#] (upgrades heavy weapons by specified amount)
; weapon_missile [#] (upgrades missile weapons by specified amount)
; weapon_other [#] (presumably upgrades other weapons by specified amount, untested)
; weapon_siege [#] (presumably upgrades siege weapons by specified amount, untested)
; weapon_simple [#] (upgrades light weapons by specified amount)
A further look around, and EB uses weapon_siege to represent reform units. With this method, the ever-present town square could give the negative bonus to all reform units, until the reform building is built. If a single building is too simple, then one can make it a series of buildings with various prerequisites, leading to the final reform building that can be built, neutralising the negative bonus. I'm still looking around for ways to tie recruitment to traits or ancillaries though.