Silver is a mercenary, who is paid by Egg Man to kill Sonic (in my Sonic 06, no time travel in it). Silver was always week when growing up but learnt that he can move things with his mind, he's also a tactical genius, he sees tactics as a game when he was growing up the more life fretening the better so he became a mercenary

before silver the hedgehog he was going to be Venice the mink and as i think there are to many hedgehogs, so i made silver back to a mink
also he's look did not come out of nowhere, this is from one of his old designs http://www.unseen64.net/2008/04/05/.....06-proto-beta/

the sword idea came from him using his psychic powers also his game play being bad