Do "normal" size modifiers apply to CMB when using a weapon?

[Blymurkla]

I'm thoroughly confused by what modifiers applies to combat maneuver checks. Right now, I'm caught up in size modifiers.

Regular attacks are modified my a size modifier. Small +1, Medium +0, Large –1, Huge –2 etc.

Combat maneuvers are instead modified by a special size modifier. Small –1, Medium +0, Large +1, Huge +2 etc..

But what about when you make maneuvers with your weapon? This FAQ states that when utilizing a weapon to attempt a maneuver, that »weapon’s bonuses apply to the roll«. The context is Combat Finesse, i.e. you are allowed to apply your Dex mod to (certain) maneuver.

The FAQ is worded rather generally, isn't it? That all bonuses you normally apply to an attack with the weapon are applied when you use it to make an attack.

Does this mean that when using a weapon for a combat maneuver, you apply both the normal and the special size modifier?

[Khudzlin]

The size modifier has nothing to do with your weapon or how you use it (unlike enhancement bonuses or Weapon Finesse). Also, the special size modifier replaces the normal one, they're never added (that would be useless, they'd negate each other).

[Mysterious Stranger]

What Khudzlin said is spot on. Another way to look at it is that bonuses from the same source do not stack. Since both are a size bonus you only use one of them. The FAQ you are referring to is talking about a STAT modifier not a size modifier. In that case the feat weapon finesse is overriding the normal modifier.