Thank you, MLN:RUGBY. Your answer is very convincing, but it means that I was looking in the wrong place. So AVOCET must substitute for EXOCET, which was my half-baked solution to "Changing ends makes object of calling a weapon". Now putting this clue into the space I originally had gives me ESPADA [A SPADE], and the puzzle is complete!
BTW, I don't know if your "Rugby" refers to the school; it was mine too.