When I was playing through Normal, I fully upgraded Listening, Health, and Weapon Sway. I fully upgraded Weapon Sway when I was literally at the final part of the game. I did had to replay the part where you are hanging upside down, because I kept missing headshots when trying to kill the infected. I know that guns and ammo are very sparse and stealth is integral on the higher difficulties. I prefer using stealth to play through the game.
A true knight, will forsake egoism and humiliate oneself with knighthood. Its only when weve lost everything, then we are free to do anything.--Tyler Durden