Professional Difficulty is an article in Resident Evil Recollections. It was uploaded on 9 April 2015.
Most people who have played the series will be aware of the difficulties up to Veteran, but Resident Evil 5 also offered "Professional" as an extra challenge.
Professional is unlocked by clearing the game on Veteran, and pretty much transforms even the weakest of majini into ridiculously overpowered beasts. Lose your concentration for even a second and you'll find yourself in dying status without so much as a warning. Stick close to your partner too because the status drains far more quickly - ragequits ahoy!
Playing on Professional does have another purpose other than bragging rights, in that you earn far more loot - if you want to unlock everything in a hurry then this is definitely the way to go...well, if you can handle it of course.