Rain's skills

Here's the basic mechanic for Rain (using a tarot deck).

There are 9 kinds of marks a player can give:

3 Physical marks (dazed, bleeding, winded)
3 Social marks (impressed, confused, frightened)
3 environmental marks (progress, knowledge, alter)

Whatever it is the players are facing is represented by the Major Arcana. Each card assigned to the obstacle has a strength. A really strong card might have +15 or +20, a really weak card might have -5 or -10.

The players apply marks by describing their actions. marks of bleeding can be given by describing attacking with a weapon, marks of progress can be given by describing moving through difficult terrain, - it's all very narration-oriented.

When the players feel like they've given enough of a certain kind of mark (physical, social, or environmental), they can challenge a card. Let's say a giant has Strength, that is +10. The players keep heaping on physical marks, describing attacks, chases, that sort of thing. After they have told a good story, and the GM is describing the giant as looking pretty messed up, they can challenge the card. They draw on of the Minor Arcana at random and the GM secretly adds the card's strength to the draw. If the total is equal to or lower than the number of marks, the players succeed and overcome the card. If they don't, they fail and can keep trying.  There's a little more to it, but that's the basics of it.

Here's the problem. I have had the players describe vaguely how they can give the different kinds of marks by using four skill sets: Fighting, Storytelling, Athletics, and Wizardry. That's nice, but it doesn't give much by way of what a character is specifically good at. Sure, a player can simply do that through description, and some players are very happy about that. But others, and I think I fall in this second category, want more of a guide: what am I good at, and how good am I?

That's my next project. The mechanic works very well, so I don't want to muck it up, but I also want to give players more to work with.