There are some solid gameplay mechanics with The Witcher 2 but some of them work and others are a little flawed. The combat system works especially well giving the player simple attack commands of heavy and simple attacks and signs, which work like spells. They are also able to craft certain items that can help them throughout the course of a battle.
The main mechanic that I noticed this with was the crafting mechanics, the player has to craft their potions, bombs and traps before every battle yet different bombs and traps do different things and different potions give the player different conditions. However the player is in forced into battle, as they are at certain points in the game, they do not have time to prepare their items. Most of the time these instances are sprung upon on the player unaware and are incredibly difficult to overcome and the last check point is the start of the battle itself.
Isolating this problem, there should be way for the player to craft their items in these circumstances. The crafting process takes too long to complete during a fight though, so the other option is to give the player a chance to escape and gather their barring before re-entering the fight.
"Youtube video showing how the signs already in the game work"