There was a lot more information about sentient weapons in earlier editions, but please restrict answers to 5th edition rules (but use earlier editions to back up statement if needed).
Would a sentient weapon gain a saving throw against spells cast against it? Per the DMG, they do have Intelligence, Wisdom, and Charisma.
For instance, normally the Identify spell would be able to tell the caster all sorts of information about an object. But the sentient weapon does not want to reveal all of its secrets and would try to resist the spell. I’m not limiting this question to Identify1, but that was a spell that leapt out at me.
1 Since spells only do what they say they do and Identify doesn’t list a saving throw. But why would it?