So, we decided we want to test a grenade that is thrown as opposed to magically launched fom the human's crotch. This thread is not about possible balance implications: For now we want the way the grenade is tossed to be as fun as possible. Balance can be adjusted by tweaking damage, blast radius and price values and should not be considered just yet.
Here is my design proposal:
You don't have to switch to the grenade as if it was a weapon. You can throw it anytime as long as you don't shoot and your rifle will be lowered visibly in both first and third person perspective. The grenade is rised from below to above your vision frustum with the left hand and the button is pushed with the thumb in the process, so that you can see it in the first person perspective. After the grenade left your vision it will be thrown from above your head, your throwing arm will enter the frustum again and leave it at the lower end before it goes back to the rising rifle (that way the throwing animation is independent of the (potentially per-rifle) lower and rise animations).
The process can be started either by hitting the grenade button once or by holding it down. The time between starting the process and the grenade being launched is fixed! During that time, a charge bar is filled in case the button is held down and it will be full at the time where the grenade is thrown (for now you can't cock the grenade by holding down the button longer but my approach would allow this to be implemented later on). The progress on the charge bar when you release the button determines the throw strength and/or angle. Hitting the grenade button once will result in a very short toss and holding it down up to the end will lead to a far throw.