Wearing gauntlets of power should allow you to wield a two-handed weapon in one hand. This does remove a big downside of two-handed weapons - the danger of them becoming cursed - though; most late-game characters wielding a two-handed weapon are probably wearing gauntlets of power already.

To solve the issue where an optimal melee combat configuration is to wear bracers and twoweapon, bracers should prevent you from twoweaponing, but not wielding a two-handed weapon.

Barbed devils have a passive physical attack that involves you getting pierced by their barbs. Possibly if you are wearing body armor and/or gloves, or wielding a two-handed weapon with longer reach, the passive attack may not always hit you. (Polearms should never incur this attack, but the way passive attacks work by default should already ensure this.)

Cursed two-handed weapons only weld to one hand at a time, allowing you to do things with the other hand. The only way to have no free hands at all is to wear a cursed shield and wield a cursed weapon.