10th level fighter, longsword in primary hand, short sword in secondary hand, no other bonuses to hit, 2WF and ambidexterity feats.
Attack 1: longsword, +8
Attack 2: short sword, +8
Attack 3: longsword, +3
Add Improved 2WF:
Attack 4: short sword, +3
20th level fighter, yada yada yada, no...