Mi pare già ci sia un errore.
In ordine:
Normal penalties: –6/–10
Off-hand weapon is light: –4/–8
Two-Weapon Fighting feat: –4/–4
Off-hand weapon is light and Two-Weapon Fighting feat: –2/–2
Ora penso al resto...
EDIT: Non avendo mai giocato un frullatore, mi viene il dubbio... si può usare un'arma a due mani ad una mano? Leggendo le regole trovo che:
1) Two-Handed: Two hands are required to use a two-handed melee weapon effectively.
2) A light weapon is an object two size categories smaller than the wielder, a one-handed weapon is an object one size category smaller than the wielder, and a two-handed weapon is an object of the same size category as the wielder.
3) Inappropriately Sized Weapons: A creature can’t make optimum use of a weapon that isn’t properly sized for it. A cumulative –2 penalty applies on attack rolls for each size category of difference (nel tuo caso, sarebbe solo un -2, ma a tutti gli attacchi)
Fin qui, i tuoi tre esempi sarebbero nell'ordine:
Arma primaria a 2 mani, secondaria leggera: -4/-4
Arma primaria a 2 mani, secondaria non leggera: -6/-6
2 armi a 2 mani: -6/-6 (due -2 cumulativi).
4) MA: The measure of how much effort it takes to use a weapon (whether the weapon is designated as a light, one-handed, or two-handed weapon for a particular wielder) is altered by one step for each size category of difference between the wielder’s size and the size of the creature for which the weapon was designed. If a weapon’s designation would be changed to something other than light, one-handed, or two-handed by this alteration, the creature can’t wield the weapon at all.
Non capisco il punto 4, che per quanto mi riguarda è scritto in sumero. Però mi fa sorgere il dubbio che non si possa...
Non vado avanti finchè qualcuno più esperto nel campo frullatori non chiarisce un po' quel punto...