To some degree, it depends what you target. A lot of strikes in FMA are to hands and such along with the "de-fanging the snake" ideology. The light, fast strike to these areas will break bones...
On the other hand, in my rather long police career, I've seen any number of subjects struck with various sorts of "heavy" impact weapons to little effect. Blows to the top of the head (typical for under-trained individuals) often glance off to one side or the other and produce vicious-looking but non-disabling cuts and lots of blood.
Drunken (or other chemically-impaired) individuals do not respond often to mere pain. Blows to the knee or pressure points or whatever that would make a sober person curl up and cry will go unnoticed.
In these cases, you need a lot of horsepower, properly delivered. Something along the lines of an elbow smash to the side of the head.
Or a Taser.....