D&D 5E Warlock Pact Weapon and Sentient Weapons

[jaelis]

I guess it comes down to two story concerns: first, I feel like making an item into your pact weapon involves a bond between it and your patron, which brings in story complications that you may or may not want to deal with. Whether that is an issue for you depends on how you think about pact weapons.

Second I do think it bypasses the item conflict rules. The item can only use its powers to influence it's wielder, and you don't have to wield it to make it your pact weapon. (I agree it is not much different here from, say, using the demiplane spell to hide it. But the pact blade effect is available at will, for free, at third level. And the hiding space is entirely inaccessible to others unless you think the patron can get involved.)

Anyway, those are the things that bother me, if they don't bother you then it isn't a problem and you can probably ignore that rule

 

[shadowoflameth]

To make a weapon your pact weapon, you have to perform a ritual that makes it your pact weapon. There is no reason that I am aware of against doing this with a sentient weapon, but it doesn't mean that the sentient weapon has to do everything you want. A sentient weapon can sometimes possess you if you go against it's goals. Think of the disadvantage if it started arguing mid fight with what you were doing. That said, the rule is specific, 'You can't affect an artifact or a sentient weapon in this way.' You can make a magic weapon your pact weapon instead of creating one out of nothingness and it goes to an extra-dimensional space when you dismiss it but again 'You can't affect an artifact or a sentient weapon in this way.'