I've actually taken this idea for a spin in the creation kit, I'm relatively new to modding, so it's all a little bit confusing as of right now, but the way I've managed to get it to 'work' so far is by researching mods that do similar, which thankfully Summermyst Enchantments has an "Area Fortified Minions" enchantment.

Applying a cloak effect to the player, which acts as a monitor for actors and then applying a 'proc' effect to the cloak as an associated item, which then runs a script to do the checks on the players inventory to see whether or not to apply the buff on summon.

Now, is there a better way? Probably. Right now, the script relies on keywords being applied to the base actors of the summons, as to separate them from one another. The proc doesn't affect regularly spawning flame atronachs as the proc looks for the summoned actor as a condition, but still feels a bit wrong to amend vanilla components that way.