The question has been asked as to whether or not a dragon can wield weapons in 5e, and for the first time in a long time, I am stumped about how to answer.
I first searched the stack exchange, finding only this, which relates to 3.5. While that is useful in terms of having me make up my mind on my own (based on the assumption that if dragons canonically couldn't wield weapons in 3rd edition, then why would an edition change alter their anatomy so that they now could), I'd still prefer to have a definitive 5th edition source to base my answer off.
The Monster Manual says this:
Assume that a creature is proficient with its armor, weapons, and tools. If you swap them out, you decide whether the creature is proficient with its new equipment.
For example, a hill giant typically wears hide armor and wields a greatclub. You could equip a hill giant with chain mail and a greataxe instead, and assume the giant is proficient with both, one or the other, or neither.
This would suggest that I could simply decide a dragon is proficient with any weapon I give it, and having proficiency means it knows how to use it, regardless of how prehensile its claws are. But is this small blurb from a sidebar in the MM introduction really the only piece of text anywhere in any 5e book that even remotely suggests it might be possible or not for a dragon to wield implements? I would've thought Fizban's Treasury of Dragons, at least, had something to explain what dragons could and could not equip themselves with, but a cursory search of that book yielded nothing for me.
I'd really appreciate a thorough answer that points me to some sources I can review myself. Answers like "DM fiat" aren't helpful in this case, because I have been DMing for 20+ years and am well aware I can just make up my own mind about this. The question isn't "what should I do in this scenario," but rather, more "does this question have a definitive answer that I've overlooked?"