Easy enough answer.
You can just cover with craft foam. Once you have it perfectly to the shape you want, coat it 15 to 20 times in a water/glue mix. This will seal the foam completely allowing you to paint it without it being absorbed.
After painting you'll need an acrylic polish which you can buy at a Walmart. It's in a floor cleaning section. After coating it once or twice, it'll give off a nice shine.
Then from there weather it by smudging the blade with black to give it a dull look. But especially to the edges and corners to make them more pronounce.
End result, it should look like this. http://s852.beta.photobucket.com/use...00757.jpg.html
Hope this helped.