Great question. =]
This exact topic is like... a third of what was on my mind while building out DI's combat systems. We want things players are able to invest in and do feel like they have an impact on the battlefield when they use them (even if that means they have to pick and choose their moments as each individual only has a few uses of each). To this end, we've done a number of things:
Eliminated all access to damage values higher than 1 on the player side. This was done because we find that when a staffer is being attacked by four people at once their exact health numbers are rarely able to be kept track of and this phenomenon is magnified immensely when hits can equate to different damage numbers. Basically, we feel that "doing more damage" for a player is a trap that doesn't actually do anything and have eliminated it.
We intend on extremely rarely giving NPC's "Resists". There is nothing fun about spending your attributes to do a cool thing and having the NPC simply state resist before the next person comes in, throws their cool thing and has it land. Our enemy defenses are very primarily planned to come through Wards. Most enemies encountered are going to have an ongoing ward to a source or two. This is done to foster a format of combat that is more about mixing and matching by working together and determining what enemies are weak to what than it is about simply beating each other with swords. As a very happy side effect this also reduces the complexity of information that our staffers need to remember (No long list of: you can resist 2 stuns, a maim, and a disengage).
Our NPC stat cards are meant to minimize information bloat so that they can actually calculate all the things they need to in real time. If I were statting 2Dawn enemies in this system for instance they would go something like this:
Special Attacks: "Crushing" 1x/5 seconds
Special Attacks: "Wound" 1x/5 seconds
Special Attacks: "Stun by Electric" every attack
Wards: Mundane, Electric
Special Attacks: "Charm by Poison: Protect me" whenever struck
With stats like that I believe even junior cast members who haven't read the rulebook and just showed up will be able to calculate on the fly everything that they need to calculate to make player action actually mean something. On the same token, the ease with which we've set up the ability to stat interesting encounters, and the ways in which we've limited player abilities, I believe means that even the more complicated boss stat cards allow for room to calculate on the fly correctly the two health numbers.
Basically, I've spent a lot of effort trying to ensure that the exact thing you are talking about is not a problem at DI.