So I was messing with Subsurf modifier to create a certain sword and then some weird artifacts began to appear (cape-like). I've tried adjusting the Crease, but couldn't achive what I wanted. Basicly, what I whant is the as on the screens, but wo any artifacts :) Also, here's the .blend file, cause I assume I didn't make myselt 100% clear. https://drive.google.com/file/d/0B0hdCv37NrtVMXU4eFB2MFFlMGM/edit?usp=sharing
You have some non-manifold geometry in your mesh.
There is a large ngon overlapping the other polygons.
Here is how to fix it:
Select the large ngons
you can either do this manually which is faster in this case since there are only 2 ngons or you could use a selection tool.
Select -> Select Faces by sides: greater than 4
Delete them: x -> Faces (3)
Select all geometry in the mesh: A
now to fix the holes: Mesh -> Clean Up -> Fill Holes
This fixes part of your problem. The other problem is the creasing. To fix this I would either use edge loops instead of creases or crease all continuous parts of the mesh rather than just single edges.