Generally, most of the combat cards of each civilization have the same effect, HP, attack or both. The only thing they deviate from is that some of them only affect civ-only units, or melee-only units, or perhaps global unit types. Like the Spanish cav, of course the name and description give it away, but due to visual imparities and God knows what, some people might be more interested in having a quick visual model that could improve reaction time rather than read 2 cards and compare.
In my effort to make the game more appealing to new audiences, and also to casual players without reading the description of each card, I came up with these designs, which are very similar to the card from the Swedish House of Bernadotte team, which looks really good by the way.
Each card that has its civilization flag affects ONLY those civilization units, otherwise it is a general card for all unit types (nat infantry, outlaw, mercenary are included)