adding to darosior's answer, and as dumb as it may sound I use substitution cipher method to encrypt my offline wallets , i am a little bit paranoid about the fact that it's possible for someone to get a hold to my PKs.
while manual substitution cipher is an old method and considered to be have the lowest security measures, it can be very handy at some point, and as long as you do it right, chances are nobody will ever be able to decryption it.
you just need to come up and an easy to remember sequence to substitute some of the characters "hex format" in your PK, make sure you never forget that the sequence , because then you will lock yourself out too.