Where is the limit on the amount of armory traits a class can take? Properties are limited, as are which armory traits a class can use by properties; however, I don't see a limit on the number of armory traits.
Perhaps it's a wording thing. It the discipline penalty just supposed to be X-1, where X is the mercenary trait value? Humanoids -> Environmental -> Cultural -> T2 seems to be the only place it's used. There it is Mercenary Class 2, which seems to always give a -1 to discipline based on the Core book sample army.
Based on the example in the Core book, you count the merc trait in addition to the 2 armory traits you can take such that this 1 trait counts as 3 total for determining the amount to reduce discipline.
Ok. I was hung up on the idea of a separate restriction specifically related to the number of armory traits based on the description of the ability.
Maximum Class Traits are listed with each class. For Humanoids that's on Page 29.
For Humanoids
Level 1 Standard Classes its 3
Level 2 Elite Classes its 4
Level 3 Leaders its 6
Level 5 Unique its 7
Mercenary Classes can take additional Armory traits above this which reduces their discipline by for each additional trait above the maximum.