Certain weapons have bonuses to perform specific Combat Maneuvers. In addition, the general rules for Combat Maneuvers state:
"Add any bonuses you currently have on attack rolls due to spells, feats, and other effects. These bonuses must be applicable to the weapon or attack used to perform the maneuver."
So, for weapon specific maneuvers, enhancement bonuses, weapon focus feats, fighter weapon training, etc will apply. This would be very useful to have a print out form or view that allowed to see the combat maneuvers by individual weapon.