It's a good point. I think I would leave this to GM adjudication, however, with a Guideline rather than a rule. If the GM feels, and the player agrees (or vice versa) that the situation resulted in a Minor Combat role then some portion of the total experience could be allotted to the characters that played the major role. However, I hesitate to emphasize this except as a somewhat rare instance. The reason why is because experience sharing is an important key to allowing lower level characters to level up along side higher level characters. Think about what happens in a 'typical' party. You might have some low level characters joining up with higher level characters (for instance when PCs get killed and new characters are rolled). Usually these characters might not expect to be able to stand on the front line. So they try to stay on the second or third ranks, or even somewhat behind the party doing various missile attacks or minor actions (that don't engage them directly in the perils of exchanging blows directly - and offers them the possibility of running away). I think once the genie is let out of the bottle, people could begin to argue (persuasively given the rule) that so-and-so didn't deserve a full share of Experience because the Higher Ranking warriors slugged it out on the front line. And so, with that argument, the higher level characters might wind up sucking up the Experience Gains, making it harder for the lower level characters to catch up with them. The quandry, as I concieve it, was solved by the Experience Sharing concept. I kept it flat and across the board to keep arguments over the allotments to a minimum. Remember, not every group is going to be equally fair minded or sensible, and not every GM is going to have the same level of Player Persuasion Power as others. So keeping the rules flat at simple may help to keep the Rules Lawyering to a minimum. That said, I again would say that I'd leave it to GMs to adjudicate in particular circumstances with an allowance to override the Experience Sharing Rule under special circumstances. Such as the one you sited. In this case a total of 48 Experience Points were awarded for victory of the Kobold and Ogre. That got spread to all the characters in your party equally, giving everyone 6 points. If I reduced Hermel's experience to Minor (half) then he would get 3 points. But how would I distribute the 3 points among the other 7 characters. I would round of course. So everyone else would get +1 point. I could do that, even though because of the rounding the math doesn't even out very well. I'm ok with fudging the numbers on decimal values, it's not a problem for me. Some GMs however might have difficulty justifying it. Not too big a deal though. One of the Guidelines should be "don't get hung up on decimal related discrepancies - just round and don't worry about the difference". I'm ok with that.
On the other point you raised, that the experience gains seems too fast... Remember that Hermel is currently 3rd level. He raised from 1st to 2nd fairly quickly. 2nd to 3rd took some time. It seems to me that 3rd to 4th is taking a while. From 4th to 5th is where you'll probably start to feel the lag. And I'd be surprised if he makes it to 6th before the campaign finishes. Not impossible, but you'll see at that time... it takes a lot of effort once you're above 4th to advance. Can be done if you're aggressive though... but then again you take a risk of dying by being aggressive. Anyway, give it some more time and see if it balances out by the end of the Campaign.
Thanks again for your thoughts! Much obliged. 🙂