To date I have been dual wielding 2 pistols, but have just tried sword and pistol to discover the following issues.
The single handed melee weapon can only go in the right hand, which is probably as intended.
However, the melee weapon is 'held' as if by an invisible pistol grip, pointing as if a long barrelled gun.
Once equipped with a melee weapon and pistol, the Inquisitor then 'glides' about, with no running animation or sound.
Submitted to bring to Dev's attention, hope it helps.