It's those toenails. They are at the very tip of each claw, very small but can rip us to shreds. They are exactly like a 1/8 long inch sewing needle. It's normally easy to clip them, but for this one I hope you would take it to the vet to have it done. Just to get you some learning time without sharp nails. It will remove one of his major destructive powers powers.
Once you are fairly comfortable with him wrapped in a towel and on your lap, you can pull one foot out at a time to do it yourself. Fingernail clippers are the closest thing we have to a good tool for this. Remember to not cut his claws, but cut the tiny sharp pins that grow out of the end of a claw.
Boy! There is much too much important information to relay through e-mails. You can read the whole body of knowledge about the green guys by reading this: