Ill caution the use of half inch, its going to be a LOT of work to move that thickness of metal by hand into a sword. If you have a striker or a power hammer go for it, but solo its going to take a lot of time and energy, not to mention gas in the forge to get a good soaking heat.
A lot of us use leaf springs for good reason, most of them are no more than quarter inch and the 5160 steel can make a nice blade for the cost so in the end if you do turn out something you think looks nice its of usable steel. Being broke as a joke myself I understand not wanting to waste good steel but most of my springs and such were FREE! the best kind. Just don't be discouraged and keep at it, mild steel can be worked and worked so take your time and learn with each blow of the hammer.
Remember to take pics, even if your not up for sharing its good to be able to look back at your work and see where you started and where the work turned the right or wrong way and where to improve and correct in the future.