The second Horseman to appear in the Bible was War. War is one of the easiest Horsemen to interpret. When I think of someone who embodies War, I am thinking of someone who has complete mastery of every combat style and weapon. In terms of personality, I can imagine this individual being like Kenpachi Zaraki from the anime/manga Bleach, which would be a berserker who is hopelessly addicted to fighting and bloodshed.
I hope you find time to visit my blog on the apocalypse