My friend was caught with a malicious weapon?

Question

He and his friend had already been confronted by a group of guys and been theatened with violence. So he took to carrying around a knife another incident insued with them and a fist fight went down. Almost immediately the boys in blue were called and found the aforementioned blade upon him. He consulted his solicitor and he said he could be looking at some time away. We would appreciate if anyone could shed some light on this unfotunate incident details will be provided if this is not quite clear. Happened in the U.K

Answer 1

He should have pressed charges when they threatened violence.

Why didn't the friend just walk away and call the cops?  Talk to the solicitor for any advice or light shedding needed.