I'm eager to see your designs, they will be far better than mine I'm sure.
One more thing: I think the Demolition Package for Pioneers should have a similar design to the Heavy Engineer upgrade for UKF. It would make the upgrade icon a bit more clear and the updated Pioneer icon would let the enemy know those Pioneers can throw satchels, so he can prepare for it.
Rough example:
Could perhaps also rename them to something like 'Pioneer Demolition Team' once upgraded, just throwing out some ideas.
Icon for upgrade was inspired by OKW upgrade icon.
But idea with new shieldsymbol seems great! I was proposing some indicator for upgrade during public itterations, like this weaponsymbol (attached below), but it didn't make it to the game. I think because it already used for recovery sappers and associating with recovery operations (iow squad can get resources from wrecks).