Well a lot of things I don't really get the purpose of, like the boomerangs. So far the best use for it I have found is trying to kill little bugs without squishing them, but that doesn't even work 100% of the time.
Poison/Tainted Meat I don't understand how to use. It seems like even when I sneak around in an area with a monster to try and place the meats, the monster just ends up seeing me, ignoring the meats and attacks me instead.
Been doing the little weapon questies to get a feel for some weapons I never tried before, and that is neat and all, but I still ended up with gunlance.
Boomerangs are pretty much there just to hit things just out of reach for you on the ground like Bugs or flying monsters. They don't do much damage but yeah. I never use them.
The Meat items only work on some monsters I think and they have to be drooling for it to work. So get them to starts drooling, put down the meat, and wait for them to eat it. Warning though if you attack them too much before they eat the meat they will just enrage and wont be tired anymore.
Finding your preferred weapon is kinda the point of those training quests. So mission complete!