The soldier doesn't say what class he is.
Then how will you know what armor bonus or penalty they are supposed to have? How would someone playing your mod be aware that they shouldn't let snipers get shot? They might lose soldiers due to misinterpreting the power suit's armor values.
You could affect their sturdiness by changing their health attribute. It's not the same, but it's similar. It also scales better with different armor suits. Consider the following:
Class 1: +20 armor
Class 2: no armor change
Class 3: -20 armor
Suit of armor 1: 20 armor
Suit of armor 2: 40 armor
Incoming shot damage: 75
Soldier health: 100
Class 1, Armor 1: receives 35 damage, dies in 3 hits
Class 1, Armor 2: receives 15 damage,
dies in 7 hits <--
Class 2, Armor 1: receives 55 damage, dies in 2 hits
Class 2, Armor 2: receives 35 damage, dies in 3 hits
Class 3, Armor 1: receives 75 damage, dies in 2 hits
Class 3, Armor 2: receives 55 damage, dies in 2 hits
Incongruencies like this happen a lot when you change armor values. An armor change can make the difference between being vulnerable or invulnerable. But giving a soldier
50% more health always makes them able to survive
50% more damage.