I have a sort of crazy theory on the Redcloaks. The thing is, it's not possible in real life, but it's supported by the books. Here it is:
The Redcloaks are former Conquerors bonded to various animals using the Bile . As the effects of the Bile began to fade, so did their bonds. Then, the Redcloaks gained characteristics from their (former) spirit animals, making them faster and stronger. They now wear masks fasioned like their animal, possibly to remember.
Now the evidence:
"Behind the horned mask, the young man 's eyes- not human eyes, but slit sideways like a ram's..." Broken Ground, page 2
"...her nails glinting, curved and sharp as a cat's..." Broken Ground, page 3
"'It was like he... wasn't human. It was as if a spirit animal was giving him strength, but there was no spirit animal around.'" Broken Ground, page 33
"...illuminating the band of scales that tapered down his forearm like armor..." Broken Ground, page 47
"It was Shane , but he wasn't the same as when Rollan had last faced him. His eyes were yellow, like a crocodile's." The Return, page 186