I'm not properly starting on the game today because I've got other projects burning for the Apocalypse Game Jam (my ongoing major game Kenoma which I made a quickstart for, and my minigame Glassmakers' Fall, which I'm wrapping up work on today).

1. Remove all non Ace-10s from the deck, each player gets their own (alternatively, just skip and re-draw face/joker cards) Suit determines which attribute/skill the card best pairs with (a 2-point bonus in the desired direction). 
2.  For non-combat actions, you draw a card from your deck. There's a currency which lets you draw more than one, so you don't auto-fail rolls on a bad draw. 
3.  For combat you draw a hand, but both high and low cards are desirable. Each of the suits ties to an attribute (brawn/speed/faith/intellect), and weapons/armor have their own attribute links. 
   1.  Attacking has card value + attribute + weapon modifier + bonus for correct suit to get a hit value that determines damage.
   2. Defense uses card value - 4 - attribute - armor modifier - bonus for correct suit, and tries to reduce an incoming attack below 0.
4. Another advantage of using the right suit is that succeeding with a mediocre card (e.g. defending on a 4+ card or attacking with a 6- card) of the correct suit lets you activate a special maneuver (e.g. parry, poise)
   1. Some of the advantages let you "donate" a card to an attacked character. They use this in place of their attack/defense otherwise, so if you're a fighter who draws a lot of faith/magic cards you can force other fighters to suffer through your crappy draw if you have at least one card from the correct suit and with the right value in your hand.
   2. A consequence of this is that you can death-spiral enemies; give them a bad card for low defense and let your buddies gank them!
5. Combat actions are abstract, and include: 
   1.  Draw a new hand 
   2. Attack + Press advantage 
   3. Defend + Press advantage 
   4. Press advantage from someone else (if they failed their attempt) 
   5. Flee 
   6. Magic?