TeacherMichelleF

Yes, I think" armour" is often used instead of "suit of armour", which can be a bit confusing. "Glass of water" is used all the time, "piece of luggage" isn't. The sentence doesn't always make the word classification clear.

Yes, basically. "suit of armour" is countable. You would wear a suit of armour but not an armour. It's like having a glass of water instead of a water or a piece of luggage instead of a luggae. I agree that it sounds a little confusing.If a countable noun (suit, glass, piece) goes first then there's nothing in the sentence to tell you that the uncountable noun is uncountable. This can be a bit tricky, I agree.

"Armour" is an uncountable noun and so doesn't need an article. Weapon is a countable noun, so it does need an article. For example, you could say "an apple" or "a song" but not "a water" or "a music" because water and music are uncountable. Does that make sense?