I was wondering about this as well. As the answer will determine quite a few design changes on the ships I usually build. Checking the bug list shows it was once listed and I've posted to it, but its listed as rejected though no reason was given as to why. Not sure if it was rejected cause it looked like it was working though it wasn't when you shot it.
Activating effect
I can jump into a docked entity and hotbar activate pierce and ion shielding it will stay on even after I exit that entity. I have tested fire weapons at it to check damage inflicted and it works.
Effect not activating but looks like it is
If I link a activation block or remote control block to both controllers and turn it on. If you hold right shift while looking at the effect controllers you can see if they are listed as active or not. However while they are active you can control the entity and see that the power is not being consumed by the defence effects. Also if you shoot them the defence effect is not applying its modifier while the controller is shown as active.
This is relatively important to any ship trying to use the ion defence effect.
Ion defence effects only protect what they are mounted on and there size required is for what there mounted on as it is and should be.
The new rail docking system is also working well with this and the transfer of damage.
Ion shield hit transfers
If you shoot a ion shielded docked entity it will reduce the damage as it should, if the hit is to big it will use shields from the mothership. The damage will be reduced by the mothership if it is ion shielded. Even if the docked entity losses all shields the ion shielding will work to the damage applied to the mothership.
Not sure what happens if you hit a ion shielded entity and it transfers the hit to a non-shielded entity. I assume or hope it takes full damage.
If you shoot a unshielded docked entity it will take full damage, if the hit is too big the mothership will also take the hit. But if the mothership is ion shielded it takes the full damage of the transferred hit. The ion shielding doesn't count for the transferred hit. I like this mechanic, as if you don't put ion shielding on externals they act as a weak point for shooting at the motherships shields until it gets under 50% anyway.
So in conclusion at the moment if you want to drop 50% shields on an ion shielded mothership shoot docked entities.
However a good designer can put those defensive effects on each external entity as well, then its still fully shielded.
Only way at the moment
However at the moment the only way I can find to activate each ion shield and get it to work, is to board each entity individually and activate them via hotbar. And if you log off they all deactivate and you have to restart them all when you log back in. Before I could either use a activation block or area trigger to activate the ion shielding on the entity. Now neither of those works, it looks like it does as it shows as active but its effects aren't applying. The wireless logic block would be perfect for this but since the logic isn't working neither does it.
From what I've been reading bobby AIs were going to eventually be able to use defensive effects but while that is nice with the rail docking system there are a lot of docked entities that we can put on ships that don't require Bobby AI's
