I used simple knife for cutting roots, while cutting them scab starts on my hands. I can used coconut oil on my hands before start cutting them but it was not effective tell me some methods to avoid this
The colocasia root (also known as the taro root) has calcium oxalate near the surface under its skin. This makes it toxic to eat uncooked and can irritate the skin.
Common methods to avoid skin irritation are oiling the hands (which isn't working for you), peeling them under running water, which rinses off the irritants quicker, and lastly is wearing gloves.
I would recommend getting a box of food grade latex gloves, that should keep your skin from coming into contact with the irritants. Doing it under running water also wouldn't hurt.