Does armor effects stack effect/percentage/nothing past 1 piece? Sleek effect?

[Accel Lex]

I've been looking at the wiki but my questions aren't answered for the most part.
The widow pieces say that the damage of poison increases the more armor pieces you wear.
The mantis pieces just say it applies Cutman and Crit Stun by wearing a piece. Does wearing 2 increase the bleed/stun done or percentage to happen? If not, is it just not worth having 2 pieces if the effect is all you want? 3 pieces gives the armor set, but what about 2 if the wiki doesn't specify increase in effect like it does for Widow armor?

I heard poison for example stacks if it's from different sources. So Fangs(Widow+Spider+Larva) Daggers stack if you hit the enemy with each of them, but hitting with the same one only refreshes the effect already done.

They said that different sources stack, so if food and smoothie have the same effect, they stack, but multiple foods or smoothies won't stack with each other.
This is what makes me wonder about armor effects. Since they're from the same category (armor), would wearing more pieces not stack and only apply the set bonus?
Does the same go for Sleek effects?

[Serpiko82]

The game just got a major perks overhaul. Wiki may not be updated yet.

[Mana Burst]

well I know the Red Ant Armor effect stacks, every piece you wear adds One to your plank/stem carry capacity.