Are you referring to a pommel/buttcap? A bolster is usually pinned on to the sides, but it doesn't sound like that's what you're asking about. Buttcaps (which really need another name, but I don't know of one) can be attached to the end of the tang via a soldered on threaded nut, by epoxy with lots of pins through the handle material, by having the tang go all the way through (though you specifically mentioned doing this WITHOUT such) an peining it over, an probably any number of other ways. I even know one Mastersmith who drills a lot of little holes in the buttcap, threads them with a tiny tap, and uses little treaded rods as pins to hold the epoxy better when the whole thing is glued to the handle. Maybe overkill, or maybe genius, but effective. Hopefully someone who actually does this can chime in.