to get a cruel bow you:
1. Find one
2. Trade for one
To get a cruel sword you:
1. Find one
2. Trade for one
3. Put a magical sword in the cube and three chipped gems/skulls, out comes a new sword with new magical properties and 3 sockets, this can be done over and over again. (ive used like 4 million chipped and never come up with a cruel anything) i hear that cruel berserker axes spawn easily, i dont know though.

Life is a waste of time.
Time is a waste of life.
So get wasted all the time and have the time of your life.