It's a lore building moment explaining how allomancy became a thing. It also makes sense that he is stronger in that he is essentially a first generation as opposed to having the ability watered down over 1,000 years. I actually think that it shows how exceptionally strong Vin is in light of...
No worries - I'm just really tired from rehearsals and what not - so sometimes I'm worried what I say sounds snarky lol. Just wanted to cover my grounds :D
Alright - I wasn’t able to sort out all my thoughts last time because of time...here’s more. The spoilers below contain major spoilers for Hero of Ages - do not open unless you’ve read it!
It could be that she's just unconcerned because she's probably swallowed worse and she doesn't really care about germs - it could be because if anyone is clean on this crew - it's definitely Sazed.
By the way - I'm not saying that consuming someone's earring is not gross :lol
I believe it's stated early on in passing that she's fifteen at the beginning of Mistborn. She turns throughout the course of the novel. I could be wrong on that - but at the very least she's 16 for the majority of the first book - if not the whole thing.