Agile Movement Passive in c3 increases attack speed and accuracy. The increase is not major at all, but the boost is nice and welcome. The description is slightly off though cos it say increases speed. Tyrant’s speed in general is very high already so the boost to attack speed is actually a better thing all in all. You can check the boost again at level 40 (Agile Movement level 2), when you shall be tyrant and you will see that the boost happens, it just isn’t a very huge one. 🙂
It is not that you do not understand, it is that you do not even question.