Giving names to inanimate objects helps the human to bond with it and have a relationship with that object. It's not unique to war. Years ago garden shops used to advise customers to talk to their plants. Most people thought this practice was funny, but the idea was for the customer to bond with his or her plant. If there was a relationship with the plant then the person would remember to water it, give it sunshine, etc.
Naming weapons is an example of the same psychology at work. If the soldier bonds with his weapon he will take better care of it. The practice continued at least as late as WW2 when pilots would name their aircraft. Even the Apollo spaceships each had unique names.
I’ve heard of it done in the Royal Navy in the Napoleonic wars. I’ve never seen it mentioned as being part of British army culture at the time.
How widespread the practice was I don’t know either
'Mons Meg is NOT enormous.Large but Not enormous.. Its calibre- I would guess- in MMS is around 100 millimetres.
In World War One the Germans bombarded Paris with a huge long range cannon called 'Big Bertha'