Hi!
How can I stop that one face from coming over the edges? I’m sorry that I can’t describe the problem any better but I hope atleast someone knows what I mean… :spin:
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You can either triangulate all mesh or put a narrow quad face ring around the hole - extrude ring and scale inwards.
Even then there likely will be artefacts on blade’s surface in render due to that n-gon you have where faces overflow.
Provide a .blend file and I can fix this problem, and send you the file back for you to study the topology method I use for making hole in strange meshes like this. I say to study with what I have finished because I don’t think I can accurately describe the method. Much better to just show!
I fixed the problem By my self sry 
And I don’t have an old save of it…