This is something I've been toying around with. I haven't tested it, but it's something I think might be worth bashing on to see if it works.
The big "Task Difficulty" chart in GURPS (p. B345) is a great example of tossing aside detailed modifiers and going with an overall feel penalty.
Using that system, the worst result is -10.*
So, what if we ditch the Rule of 16, and essentially maximize the penalty for all contests equally at -10?
Rule of 16 becomes the Rule of -10. In addition, any Quick Contest of Skill that imposes a penalty (to resist, for example) has a maximum penalty result of -10. The biggest penalty you can roll against from a singe source is a -10. Apply this maximum after figuring out all relevant margins of success.
Feints, Beats, and Ruses work normally, but the penalty caps at -10.
In a generic Quick Contest, ignore the Rule of -10. The Rule of -10 is the maximum penalty you can suffer, it doesn't limit the margin of success in a contest to determine who wins/loses by the best amount. If someone succeeds by more than 10, don't limit it to 10.
Rule of 16: Caster has an effective Sleep-22; caster rolls a 9, makes it by 13. Opponent has HT 16 or under, so skill caps at 16. Caster actually made it by 7 and the defender has a -7 to resist. If the opponent was, say, HT 19, the caster would have made it by 19-9=10, for a -10.
Rule of -10: Caster has an effective Sleep-22; caster rolls a 9, makes it by 13. Caps at -10. Done.
RAW Feint: Attacker has Broadsword-15 and Feint-19, and rolls a 5, making the roll by 14. Opponent makes his skill roll by 2, for a net margin of failure of -12. Defender has -12 to defend.
Rule of -10 Feint: Attacker has Broadsword-15 and Feint-19, and rolls a 5, making the roll by 14. Opponent makes his skill roll by 2, for a net margin of failure of -12, caps at -10. Defender has -10 to defend.
RAW Generic Quick Contest: Two characters roll a quick contest of skill. A has Skill 25, B has Skill 23. A rolls a 10, making it by 15. B rolls a 12, making it by 11. The net margin of success is -4.
Rule of -10 Generic Quick Contest: Identical to RAW.
- calculating resistance to a magical spell should be easier, since you only need one comparison to determine the needed margin of victory to resist.
- spells get extra potency, but aren't overwhelmingly potent. Higher spell skill levels may make a -10 to the resistance a fairly common occurrence but the cap and the limited annoyance of casting a skill 18 spell vs. foes with resistances of 18, 16, 12 (for example) should make up for that.
- Feints, Beats, and Ruses remain potent, but cap at a very-harsh -10 and can't beat defenses down to a ridiculous degree. This effectively caps the useful maximum defenses in the mid 20s, but defenses rarely reach that. You'd need to stack on other effects (Deceptive Attacks, Stunning, etc.) to deal with ridiculous defenses. This also means that high-ST Beats can only do so much, so a ST 50 dragon vs. a ST 10 human can only inflict a -10 to defend, not a (near-)automatic failure.
- Generic Quick Contests are unchanged from the RAW.
- Perks like The Rule of 17 might need to become to This One Goes to -11. That alone makes this rule potentially awesome.
Like I said, I haven't tried this, but I kind of like it.
* With the caveat that p. B488 says you can go as high as -15 or -20 in a high-skill game. I'm ignoring that in this case, because a flexible limit is fine but not what I'm suggesting here.