Nano-technology - Not Sufficiently Advanced, as per the Arthur C. Clarke gold standard of sufficiently advanced technology.
The proper names and descriptions of a sword’s parts.
While we’re talking about the subject of constructing religions, I’d like to bring up the concept of the Creed. The creed is nothing more than a simple statement of the religion’s beliefs, meant to be recited. If you cannot write a creed for your monotheistic religion, it probably needs work on internal consistency. Creed examples:
The player characters, experienced and somewhat well known, hear rumors and travelers' tales about a distant area being overrun by dragons (or other terrifying monstrosities). The locals have sent them a message, begging for heroic aid.
When they investigate, they discover that nothing of the sort is going on. It turns out that a group of thieves wanted them out of the way so that they could rob them (or someone who would normally receive their protection).