Full disclosure, I can't take credit for these. One of my players came up with the idea for them after becoming enamored by an older indie game called Riddle of Steel. I'm not using them in our game as of yet, since I haven't had time to playtest'em and I want to wait until I start my next campaign.
(Pardon the some of the text in the images, I'm having trouble with the fonts in SE at the moment)
The idea is that weapons are more or less effective depending upon the type of armor they are going up against and how they are wielded.
For instance, a spiked warhammer would be much more effective against chain mail than the blade of a slashing arming sword. However, a "hand and a half" sword when grasped by the blade nearest the hilt and used in a thrust would be more effective against plate than a club.
To reflect these qualities, each weapon has a selection of combat types, including Cut, Thrust, Bludgeon, and sometimes even Parry. Each mode adds some advantage, or disadvantage to the attack roll and damage dealt.
The arming sword below offers an additional fortune die when used in a cutting attack and has a damage rating of 8. If used in a thrust it offers only a damage rating of 5. The blade also offers an additional defensive ability when used in combination with a block or parry action in the form of a black misfortune die to the incoming attacks die pool.
At the bottom of the card are basic stats that are used if the player does not announce the type of attack he his going to make.
Now overall this increased the deadliness of most weapons, making killing an unarmed and unarmored man disturbingly easy. However, I feel this does a good job of reeling in 3rd Editions tendency to play it safe with the PCs lives depending upon the careers they've chosen. However in my campaign I want the Roadwardens and Apprentice Wizards to feel just as uneasy as an Apothecary or Peasant when faced with an armed opponent.
In combination with armor cards (below), which add damage rating penalties to the various attack types, the system tends to balance itself out assuming the opposing combatants are both wielding arms and wearing armor.
The added choices of attack types also allows my more strategic and combat oriented players to roleplay their attacks more vividly, and allows me as the GM to descride inflicted wounds more gruesomely! Squee!
There's also the addition of of armor and weapon wear and tear which is tracked on the armor cards using a built in tracker using a paper clip to track the armors degradation. Since I sleeve all my home brewed cards, I just give the player several different qualities of each type of armor stacked together in the same sleeve. When armor is repaired or damaged sufficiently, they just swap out cards to reflect the changes to stats (the more damaged the armor, the worse it is at soaking up damage).
For weapons I just decided to have the players track how often they've used a weapon during combat encounters with paper clips. When a bladed weapon has aquired five or more clips it must be sharpened or suffer a -1 to damage for every clip over the limit.
I know this seems like a lot of record keeping, but most of it can be done quite quickly during a rally step, or even saved for the end of session, and for me it adds another facet of grittiness to the setting...bloodier and deadlier combat, and the need to constantly hone and take care of your equipment so as not to lose what little advantage it provides against possible death or maiming.