What Nightwind & Mackenzie said.
The only thing all pagans have in common is that they're not Christian, Jewish, or Muslim. Pagan is commonly referring to someone who follows a polytheistic religion - but then there are many polytheistic religions, all with differing beliefs and practices.
"he basically believes in the earth" - That's a ridiculous statement. I don't know how anyone could not believe in the earth. Are you sure that's what was said? Or was it more like, "believes in the gods of the earth/nature" or "reveres nature" or something like that?
If this dagger that your aunt pulled out to joke with belonged to her boyfriend and he considers it one of his spiritual ceremonial tools, then I'd say what your aunt did was highly disrespectful.
Wiccans use these daggers, called athames, for directing energy - not for cutting anything. Perhaps other types of pagans do as well.
Honestly, you'd have to ask him more specific questions, because "pagan" is too broad a term, and we obviously don't know him so we can't tell you what he believes and what he does with his personal possessions.