The idea is to behave the same way as the flux - killing one health bar leaving others intact - differing simply by what HP bar you are disrupting.
I gave a Focus Belt-style effect to keep it from killing vehicles, since they don't seem to have any structure. (obscure reference, I know)
the tech section explains how it gets around the shield systems, if that's the part you're worried about.

It appears people have missed the point.
Yes, shields usually block weapons before reaching armor.
And I KNOW that other weapons hurt shields first.

This grenade is NOT, repeat NOT, meant to directly kill or replace AV in overall effectiveness.
What it is meant to do have a similar ability as a flux grenade, simply against armor instead, Without Touching Shields AT ALL.

That doesn't make any sense because shields surround armour, to get to armor you have to go through shields so there's no way this idea could exist in new Eden logically as it makes no sense for someone to be shot in the heart with a bullet that completely ignores body armor

The one shotting of shields with the flux is bad enough, imagine the grenade spam we would get if one of each was all you had to have to kill anything on the field.

Nothing can go through the shields without taking them down first and it wouldn't make sense otherwise.

In EVE there is a skill called tactical shield manipulation that changes the point at which damage "bleeds" into armor through shields.
So in the EVE universe you can damage armor while shields are still there so they could easily justify an anti armor grenade.
OR
These grenades could be super powerful against armor but require that the target be low on shields already.
Flux grenades remove the strongest point of Caldari tank so you need to get out quick if one hits you.
These grenades would do the same for armor. Got a pesky Gallente HAV rolling around with no shields but armor tanking like a boss lob one of these and their armor goes way down and suddenly they need to GTFO.

@ghost-33 the shields are designed to stop basically every offensive energy type so whatever goes through the shields would theoretically be harmless)

@xinera xios there isn't much of a description besides saying it magically ignores shields

The flux is balanced simply because shields regen without a module, so the same concept on armour would be beyond OP

I forgot to mention in the tech description of OP that, because it disguises as repair 'bots, the defense CPU of the target vehicle allows it to get through shields.
It still follows your logic, because the system thinks that it is harmless, even though it really isn't.