[Crakkerjakk]

It's tricky. In all honesty there's pretty much no martial art that will prepare you to go up against someone significantly stronger who can ignore most injury. I think FMA is pretty close, as at least it strongly emphasizes weapons and "trapping" of limbs by moving to areas where the opponent has difficulty applying his full strength. However, there's still the assumptions on how joints work that may or may not apply to various supernatural entities.

In my opinion, FMA is the closest you're going to get because it's the most heavily weapon-based art I know of that's still fairly close to it's roots as actual pre-firearm combat training.

Any modern military style is going to focus less on hand-to-hand fighting than something that existed before guns, with greater concentration on sentry removal stuff. And the whole "defanging the snake" bit with FMA is not really that heavily emphasized. It's in there, but it also includes a lot of quick closing and close-in knife work to vital bits in the body's core. And various supernatural critters MAY still be susceptible to pain from the touch of whatever can kill them, even if they don't take injury unless they're stabbed somewhere specific. If that's the case, a focus on weapons will pay off well, IMO. So that'd be my recommendation.