If you're talking about real-life martial arts, then Hung Ga is a great martial art to accompany Body Armour Proficiency. Since Hung Ga focuses heavily on defence and strong stances, it can really pair well with someone who is proficient with body armour.
Another martial art that is good for defence is called Silat, it is relatively unheard of but it is very popular in my hometown of Indonesia. it too focuses on defence but it is more acrobatic as it involves kicks, unlike Hung Ga which is heavily focused on fists while making sure that the feet stay firmly to the ground.
There are some other martial arts which are similar but I am not very familiar with any of them, you could always google them if you wish to find out.