"The FMA guys train for flow, movement, reflex and hard, accurate strikes. They don't do much conditioning, if any. How does one "condition" against the slash or a sharp edge, a bonebreaking strike from a stick (or the bullet for that matter...?"
I usually stay fairly quiet on this forum, but once in awhile something comes up that I can discuss intelligently. My main focus is the Filipino arts, and I live in LA, a major center or FMA activity. I train at the Inosanto Academy, a well known school.
Many FMAists don't really condition themselves much against these things mentioned, except mentally. I have seen a major change in the way I look at fighting just by being told about knives and their effects by people who have faced them or used them for real, and by thinking about their nature, and realizing that a successful defense against a knife may still lead to many stitches and perhaps a need for a few pints or of blood or plasma, especially if the attacker is skilled, or, unskilled, but jerky, vicious, largely uncommitted in their attacks, and unpredicatable. I think that with many FMArtists, the mental game is especially important, and the willingness to accept that you must keep going evne when you are hurt in order to survive is a major point of importance.
A sidenote: Several months ago someone who had once studied at my school for eight years but who had been away from training for (?) years was attacked by a mugger with a knife. He was badly wounded, but disarmed and incapacitiated his attacker, and was able to get help in time to survive.
Many of us are hobbyists and not that willing to open ourselves up to serious injury in training, and with a weapons-based art the potential for injury is (for the most part) far greater than the injuries a kick or punch can give.
Still, there are exceptions. We have almost totally unprotected sparring at my school for those who want it. Fencing masks, cups, gloves (or field hockey gloves), and knee pads are used with fairly light sticks. I have not yet done this, but I believe that only stick attacks can be done here. I know of other schools that do similar training.
For those who desire, the Dog Brothers (also students of my school for the most part) do similar sparring, but with heavy sticks, and no rules. They do three minute rounds and in addition to any mutually agreed upon non-sharp weapon(s), any physical attack can be used. I have seen one gathering of the pack, and while bruises and welts are the rule, sometimes bloody cuts, stitches, bleeding lumps, and broken bones are inflicted. These gatherings are open to any who wish to enter.
BTW, many fights at the Dog Brother events often end up on the ground. Even a skilled stick fighter may not be able to drop a dermined foe before he closes. Even a solid blow or two from a heavy stick wielded by a skilled fighter may not drop an attacker. Many of those who are taken down are skilled at unarmed arts that among other things employ knee srikes. There are lessons to be learned here for those willing to cross-train.
Also, most FMArtists I know study at least one other style. In truth, we tend to be big proponents of cross-training. The FMAists I know of have all sorts of arts in their backgrounds. Many study arts that involve sparring with heavy contact, like Muay Thai, Western Boxing (the Filipinos have also been pretty into boxing), or Judo. Such arts especially teach pain, and how to endure it while dealing it out.
I am not yet particularly hard-core in my training, but I am an intermediate level student in Bruce Lee's fighting style, and do a bit of Muay Thai. I have eaten more than a few painful blows, and my training will only escalate this tendency. Still, even our gentle training in the unarmed part of the Filipino arts often involves (at least for me and other demonstaration types used by the teacer) being the recipient of light to moderate blows to the kidneys and various nerve clusters, or painful joint locks. We are conditioned to pain to some degree that way, as well as by the very frequent errors in our two person drills that lead to hand shots, or blows to other areas. I can't count how many times my fingers have been nailed by someone's stick. I have met more than a few who have broken fingers, though thankfully I have escaped that fate. Some with broken fingers still train.
Anyway, the above may help you understand a bit about how some FMArtist learn to live with pain.