Photoshop :: Blowing Up Texture And Sharpening It

I mod this old game and the textures are low res, they are alright on characters but the weapons get all fuzzed and horrible, it looks like nothing has changed from when they were low res.

i am doubling the size here. possibly tripling if the game will allow it. but they don't seem to really make a difference even when i try to smooth them out or sharpen them up. I use High pass and maximum, and then put them both on soft light over the original texture, before merging them and using unsharp mask.

How to make them look better when i'm doubling the size. using JUST photoshop, i can't afford all the fancy plugins at the moment.

here's a visual example for you:

Low Res:
ScreenShot8.bmp
High Res:
ScreenShot1.bmp

there's virtually no change. fix this little problem Vbulletin has with.bmp files?