AGI attribute itself is powerful. Above all, if you get used to Parkour, it will essentially be a 100% damage avoidance skill.
Jokes aside, Parkour itself is very powerful, and the newly added Hard Target can reduce damage even if you are pressed against a wall by simply pressing a movement key, so it is only slightly weaker than Pain Tolerance. Furthermore, SMGs can be created the fastest out of many Tier 3 guns.
Knives are also extremely powerful among melee weapons, and since they consume so few stamina that you don't need to take the skill, you can focus on gun skills without waste and contribute to the speed of creating SMGs.
AGI Mastery? Rather than taking it, it's overwhelmingly better to put it into FRT and aim for the synergistic effect of Pain Tolerance and Hard Target.