Traits are additional "special attributes" which certain players had in Fifa08, for example Michael Owen of course has "injury prone", he also has IIRC "tries to beat last man" and a couple of others, Mark Viduka on the other hand had "target forward" meaning he tried to get on the end of high balls played into him, in Fifa09 none of these traits are visible, there is no section to view them, there is no section to edit them, I know for a fact players in the database were assigned traits because I assigned them to my four teams, so the question is: did EA do away with traits completely or traits are in Fifa09 but they're hidden away so you don't know what special qualities a player has until you play against him or sign him?
I'll try to find out the answer from my EA contacts.