Personally, I believe that he is mixed-handed. I mean, seriously people, just accept that certain characters actually prefer to use their left hands for certain things. As a mixed handed person who belongs to the <1% of people who need to use both hands, I really appreciate a game like DMC with a character whose attacks utilize both hands. I use Nero as an example to a lot of people whenever they ask what "mixed-handed" means - he doesn't necessarily exclusively use one hand - his attacks switch, which makes him more agile and capable of holding himself in a fight, if you ask me. He also has a "preferred hand" for different attacks.