It works like this.
The Insect Glaive relies on inputs from you and your "Kinsect" with the Glaive in general, it's used for hitting stuff with alot of combo potential, also using the Glaive gives you access to pole jumping, this is really REALLY useful for mounting on big monsters.
However, your Kinsect works in a different way, you can launch it from your arm and try to aim it at specific parts of the monster, doing so will do small damage to the monster and can nab you various buffs to your hunter when you call it back, there's a few buffs that do the following when the Kinsect hits specific parts, also I believe hitting the monster in the areas I mention should give the appropriate buffs.
White = Speed increase (Hitting the Monster's legs)
Red = Attack increase (Hitting the Monster's head)
Orange = Defense increase (Hitting the Monster's body)
Green = Small heal (Hitting the Monster's tail)
However this might change on some bosses
You can also fire a small projectile and doing so will make it easier for your Kinsect to aim for that specific area, like if you wanted to heal up only, you'd have to hit the monster's tail with it and you'd get Heal ups alot easier.
The Glaive's combo possibilities are important to maximize the damage you can do, if you want to keep things safe, you should probably rake up some buffs (you can hold up to three slots of one of each buff, however Healing doesn't count) and then go for the offensive side as the Glaive offers no sort of shielding whatsoever.
I dunno if all this helps but I hope I managed to give a basic view of the weapon, it's really fun to use but it's more of an advanced weapon since it requires alot of patience to use and you need to have a good idea of what the monster's attack pattern is like to ensure you're going to live as you'd be playing a big role in the hunt.
Also @ Mudkip, if you ever wanna hunt for Gore Magala materials to make his weapons and such, give me a ring and I'd be more than happy to help you out.
This is perfect, thank you!