Can confirm that there is no way to visibly toggle one-handed mode for a 1d8+2 weapon damage. This is superior to GWF with 1d10 because your dmg range is 3-10 base vis a 1-10 base. A base 17 STR fighter will run 6-14 damage (average of 10) vs 4-13 (avg 9) and Dueling can still use a shield.
