Despite looking like a ghoul (and apparently not far from it IRL), Capistrano's feat there at the age of 70 was actually pretty impressive. Guy was literally in the frontlines commanding people.
Rather than wounds though, he survived the battle but ended up dying of the plague like Hunyadi did. Surprisingly, Capistrano managed to outlive Hunyadi by almost two and a half months (August 11 vs October 23).