D-Links.
Think about it: it makes more sense for Sora to have this gameplay mechanic because of his literal connection with other hearts.
I get where this sentiment is coming from, but I also kinda feel D-Links should stick with the Wayfinder trio. Mostly because Aqua actually
invented D-Links herself. It was said in the very first cutscene that we saw the Wayfinders, that she imbued them with that magic, thus allowing the BBS trio to reach out and harness the strength of their distant companions. An "unbreakable connection." In that sense, I think it'd probably be more appropriate for D-links to stay with the BBS trio for the time being. Sora has similar abilities, I agree, but I also think the nuances are a little.. different. If that makes sense.
With Sora, I'd say Summons/Links (from KH3) are far more in-line with his style of drawing on others strength. He's always been more prone to summoning his friends and teaming up with them, rather drawing on their powers to augment his own
directly. A good example of this would be in DDD, where Sora summons his Dream Eaters to do a team attack-- similar to Limits in past games, and Riku fuses with his Dream Eaters and combines their strength with his own (highlighting the subtle thematic differences between "My friends are my power!", and "strength to protect what matters.").
In terms of adapting the kind of mechanics you suggested, I honestly think Xion would be a
perfect fit. Not only can she already make copies of everyone's weapons at will (something Sora, to my knowledge, has never been able to do), but she can also cannonically draw on/mimick their powers in a way that'd be perfectly in line with what you wrote. I.e. Summoning Aquas Keyblade and using Spellweaver, for example, would be something she could already feasibly do without it coming out of nowhere.
Also, this way, we're giving more characters their own unique twist on familiar ideas. Which has the added benefit of keeping things fresh and allowing everyone to develop their own defined playstyle.