A machete may be considered a weapon in certain contexts, but that's not a unique law. The US also reclassifies things as weapons once they are used as weapons (in that instance.) Attack someone with a machete and it suddenly becomes a deadly weapon.

Canada bans a lot of weapons for looking "scary" -- nunchuks and butterfly knives for example (both of which are rather notoriously more dangerous to the person wielding them than anybody else). Americans who come to Canada are frequently surprised by the different laws up here. Yes, an attack with a machete renders it illegal in both countries. A concealed machete is illegal in Canada, regardless of intent or use. I'm not so sure about the US (especially with the variance among state laws)

A lot of states ban nunchucks (sometimes as "ninja weapons") and butterfly knives. It's highly variable throughout the US.