I'm tossing up the idea that sometimes an action might have an inherent difficulty associated with it.
Such difficulties would be between 1 and 10, if the difficulty die doesn't reach this score, then the action suffers a negative side effect. This basically turns the final result into a "no, but..."/"yes, but..." verdict. You might do it, you might not, but the chosen feat to complete the task obviously wasn't quite the right one for some reason that is only revealed later. A player could pull out at this time, but will suffer some repercussions.
On the other hand, if the difficulty die does match (or beat) the static difficulty, it has shown that this type of action is on the right track, and if the skill roll doesn't succeed then a team-mate will gain an advantage on their follow-up roll (basically an "and..." result)
Both players roll their difficulty die (the higher result here indicates the more spectacular feat being attempted)
Both players roll their skill die and try to match the result of the difficulty die. This is a hit or miss affair, either you succeed in the feat or you don't. This is a strategy for the round.
"Simple strike" and "Defensive stance" might both be d4 feats (the former inflicting base damage only, the latter reducing incoming damage by 4)
"Balanced offense" might be a d6 feat (inflicting base damage and reducing incoming damage by 2)
"Armour piercing" and "multiple opponents" might both be d8 feats (the former inflicts damage that ignores armour, the latter allows base damage to be inflicted to two opponents)
Both Ed and Diana have experienced combatants with d8 combat skill.
Ed goes for a "Balanced offence (d6)", Diana goes for "Armour Piercing (d8)".
Ed rolls a 5 on his difficulty d6, Diana rolls a 2 on her difficulty d8.
It doesn't matter, even though Diana is attempting the more complicated task, but she's obviously seen a better opening in her opponent's defenses.
When is comes to skill rolls...
Possible Outcome 1: Ed rolls a 7, Diana rolls a 5...both beat their difficulty dice so both actions occur. Ed's strike hits but is blocked by the entirety of Diana's armour, Diana's strike hits and even thought it completely avoids any armour, the damage is reduced by 2 points because Ed is expecting it and has avoided the worst.
Possible Outcome 2: Ed fails his roll but Diana succeeds in hers. Ed doesn't manage to get in a hit, nor does he manage to anticipate Diana's move in any way. Diana's strike avoids all armour, and doesn't suffer the damage reduction due to Ed's careful footing...full damage goes through.
Possible Outcome 3: Against the odds Ed succeeds but Diana fails. Ed gets in his strike it is absorbed by the maximum level of Diana's armour, Diana's attempted strike does nothing.
Possible Outcome 4: Both Ed and Diana fail in their attempted feats. By all rights, this would be one of those "whiff" moments, where nothing much really happens. I don't really want "dead rounds" to occur, so maybe the higher rolling skill die earns a strategic advantage that offers a bonus in the following round.
Some things to ponder. I think this might be a more elegant system than the "System 4" idea I've been working on.