Things that can pierce old fishing gear beside coastal region (8)

I believe the answer is:
bayonets
'things that can pierce' is the definition.
Although both the answer and 'things' are nouns, they are not in the same form of the noun.
'old fishing gear beside coastal region' is the wordplay.
'old' becomes 'o' (abbreviation).
'fishing gear' becomes 'nets' (I've seen this in another clue).
'beside' says to put letters next to each other (I've seen this in other clues).
'coastal region' becomes 'bay' (I can't justify this - if you can you should believe this answer much more).
'o'+'nets'='onets'
'onets' after 'bay' is 'BAYONETS'.
Can you help me to learn more?
(Other definitions for bayonets that I've seen before include "Knives fixed to the ends of rifles" , "Daggers fixed to rifles" .)
