As far as I am aware, something unlocks additional unit traits that I can use when designing my units - I think it might be tech related.

If it is, the traits that become unlocked should be shown on the tech tree.

I was thinking that I wanted to have a unit with 'Brute' which I've seen previously gives the unit an attack bonus against things with lower strength. I tried to look it up in the hiergamenon, and there does not appear to be a section about traits.

I would like to see all the possible traits listed in the hiergamenon, and whether they are available to units (and how to unlock them), and whether they are available to heroes (and what the requirements are for them to have a chance of being offered on level up).