I'm trying to reproduce this spesific SFX, but i couldn't figure out how to create that scrape. Regular sword (fish slice) scrapes just won't work. Any ideas?
the sound: http://snd.sc/PbYGrV
On top of the other suggestions so far, try the knife on many surfaces. If it's not a knife you care about, use brick, stone, soil, gravel, various woods, vegetables, etc. to cut into/scrape against. Come to think of it, I wouldn't suggest using one of my good knives for this anyway ;).
Do you have a sampler plugin or something you can use to map out sounds to a midi keyboard? It takes a little more setup time, but this is one of my favorite ways to quickly audition different combinations of sounds. Grab your favorite cut/scrape samples and assign each to an octave of the keyboard (C to C). Put the default pitch at F#. This lets you freely play with layering of sounds AND pitch shifting up to 6 semitones simultaneously.