It wasn't the kind of pain that cripples the body.
The Void was comprised entirely of darkness element and just like an Abomination, Derek lacked pain receptors. What tormented him was an aching of the mind, caused by the constant corruption the spreading Chaos inflicted upon him.
The Cursed Element didn't just turn the darkness into more Chaos, it also twisted Derek's personality. The lack of light element marred an Abomination's life force until it affected their psyche.
The effects produced by the alterations were completely random. Some Abominations became geniuses. A few found enlightenment. The vast majority of the Abominations, however, became raving mad.
'I need to feed, but not on humans!' Derek thought, his mind echoing with pangs of hunger and Ezio's laughter.
The Void could almost hear his Earth's father mocking Derek for his weakness from the grave. It was the reason the Void avoided human settlements.