[2021] how to improve iron skewers in 7 days to die

I'll be honest, I'm not even sure what is is they're asking.

Do you mean the Iron spike traps?
How did you want to improve them?
Are you looking at modding, or just some in-game upgrade path?

Originally posted by Pancho Pantera: I want to improve them

There is no upgrade path for them. If you want to do anything more with them, you will need to mod the files.