In the case of shrapnel I guess I always assumed it was derived from some World War era Germanic word for metal scrap/shards, so that it's just named after a British dude is pretty unexpected to me.

I swear I correct people about Elo vs ELO two to three times a year.

And yes I am a great party guest!

Saxophone is just as unexpected, other -phone musical terms, like vibraphone, idiophone, membranophone, come with a prefix unrelated to people.

Sadism and masochism - perhaps less unexpected, but no less than shrapnel IMO.

Vibra-, idio-, membrano-, aero-, etc. are existing or obvious prefixes. Sax- is not. All I can think of is Saxon, but saxophones are pretty recent, so that doesn't match.

Sousaphone is another -phone that's pretty obviously named after a person. Less well known but still pretty obvious are rothphone, heckelphone, sarrusophone, sudrophone.

All my life, I thought "sadism" had to do with the word "sad"!

Santorum literally screams eponymous neologism.