First, the basics:
Cold Iron characters have attributes, skills, and proficiencies, in a rather D&Desque way. Skills are sort of the equivalent to character class in D&D, except rather than each class providing both fighting ability and whatever else, in Cold Iron, everyone has a fighting skill, and usually has a magic skill (there is a passive magic skill which provides some knowledge about magic, and factors into saves). Proficiencies mostly come into play for fighters.
This is the area I've diverged from Mark's rules the most. In Mark's game, profficiencies were treated the same as skills (you could put XP into sword proficiency just as well as fighting proficiency). Fighting skill granted some XP to put into proficiencies (the default was you had one proficiency equal to your fighting skill, or you could break it down). XP for skills follows an exponential curve (doubling each level). In Mark's rules, spell casters were potentially just as good fighters as non-spell casters. Other than riding proficiency, some reference to scouting skill, and a humor skill (which was a catchall for social skill/charisma stuff), there were no other skills or proficiencies detailed (though I think they did exist, and you could ask for them).
The basis for attribute generation is 3d6 for each attribute, with an additional 1d6 added to that to get a "potential". 1st level characters got to raise one attribute to potential, and each skill level beyond first allowed increasing one attribute one point toward potential. Of course most campaigns ran with things like roll 4d6 take the best 3.
One issue that bugged me from the start, partly because in every game I ran in, I got hit by it, was that with random generation, it was quite possible to wind up with a character who had no hope of being a spell caster, who also didn't have quite as good physical attributes as the spell casters. I found it very frustrating to run a character who was basically good at nothing.
This resulted in a big change in how I ran proficiencies. I set it up so fighters got the equivalent of 2.5 proficiencies by the old system. I split the proficiencies in half mostly, so a fighter actually got 5 of my new proficiencies (shield proficiency became a double proficiency). Clerics got 4, and mages got 3. I also added in all sorts of side skills, and proficiencies for them (scout, thief, alchemist, and more).
I also structured the rolling so a player declared what they wanted to roll up (fighter, cleric, or mage), and then we rolled until the attributes looked good. I began to observe a problem though that I've noted in long term campaigns with rolled attributes. As the campaign goes on, the average of the rolled attributes slowly creeps up. This is due to a variety of issues, mostly player driven (but some GM driven).
When I resurrected Cold Iron a few years ago, I decided to go to a point buy system. I came up with a point total that allowed one to just barely build a perfect fighter (18/24 in Str, Dex, and Con). The perfect fighter would have no spell casting ability, probably a 10 Will (for magical defense), a 10 Alertness, and below average MP.
I've been noticing a problem now though. The spell casters can't fight their way out of a paper bag. They wind up with 10s, maybe 12s in Str, Dex, and Con. Combined with a limited proficiency set (I have also changed the way proficiencies are handled, mostly a simplification), we discoverd the cleric was more a danger by trying to help in combat. The mage (who has slightly better fighting skills) surprised us all by actually rolling well in one combat and doing a bit of damage.
With my recent revision, I set it up so that the interesting non-combat stuff does not detract from combat ability much at all. A non-spell caster can be a scout or thief, or they could take combat riding (fun, but not overly usefull), or they can get a bonus to charisma/renown (charisma is now just the characters best skill, plus renown points earned in play), and a few other abilities (everyone starts with 2 abilities, non-spell casters get another at 5th and again at 8th). A character can choose to have minor cleric abilities (paladin sort of deal) as an ability (and then they get no more abilities in the future, cleric level is limited to 1/2 fighter level, they get full fighting proficiency).
One thing I'm thinking of doing is getting rid of the big distinction in fighting proficienct since the point buy makes the caster trade off fighting ability attributes for spell casting attributes. But I think I also need to do something about the attributes. One way would be to get rid of Talent (mages) and Faith (clerics) and run all the magic stuff off Will, but that gets rid of dump stats (though casters will still want more MP than the fighters). Another would be to make the attribute points non-linear, so the spell caster who is spreading out amongst more attributes can still take decent attributes (but I worry that that might make the fighters more generic - but maybe it just takes the "perfect" fighter off the table, which might make the fighters more distinguished).
Getting rid of attributes alltogether would be a solution, but that would be a radical change to the game.
Another possibility might be to throw out the point system for attributes, and just create sets of attributes that don't necessarily add up to the same point value. With such a scheme, a kick-ass mage might have 18/24 in Talent and Will, and say 14/16 in Str, Dex, and Con (and perhaps they can trade off between Str, Dex, and Con), an 8 Alertness, and 36 MP. A cleric would have the same values, but Faith instead of Talent (or maybe Faith gets ditched). A Less kick-ass spell caster would have 16/20 in Talent and Will, 30 MP, and 16/18 in Str, Dex, and Con, and an 8 Alertness and can trade off Str, Dex, Con, and Alertness. A kick-ass fighter has 18/24 in Str, Dex, and Con, 8 Talent, 10/14 Will, 8 Alertness, and 16 MP. A not quite so good fighter has 16/20 in Str, Dex, and Con (and can trade off), 8 Talent, 12/16 Will and 12/16 Alertness, and 22 MP (and can trade off Alertness, Will, and MP [MP 2 for 1]). A warrior-cleric gets 16/20 Str, 16/20 Dex, 12/16 Con, 14/18 Faith, 12/16 Will, 8 Alertness, and 20 MP.
This way, the non-spell casters still get ok attributes, but clearly are lesser fighters. They will also probably be a level lower in fighting skill, so even if they get as many proficiencies, they are still definitely second class, but can fight their way out of the wet paper bag.
Another way to play with it might be to make Talent, Will, and Alertness cost 1/2 points, and maybe make MP be 1/3 points instead of 1/2. With points kept so the "perfect" fighter has trouble getting better than Talent 8, Faith 8, Will 10, Alertness 8, and MP 16, it might work pretty good. This would also help the thieves and scouts (who definitely want decent Alertnesses). And it might make for a few fighters that have average or better MP.
Hmm, another thought would be to take MP out of the point buy. Non-casters get 20+Passive Magic Level MP. Clerics get 26+Cleric Level. Mages get 26+(Magic Level +1)(Magic Level)/2 (and then maybe I also get rid of the mages focus and one of the nasty equations). Since clerics also get spell points, which have a geometric progression, they are going to be on par with the mages.
I need to look into this... I think I may have a solution...