What is it with this guy and Keyblades?
The Keyblade he inherited the ability to summon from Terra was the Kingdom Key, which despite Nomura refusing to say it outright, must be special since it is by far the closest KB to the X-Blade, which all KBs are based off of.
When he lost it to Sora he was still able to summon a weapon with a Gazing Eye on it, or at least something related to the KBs with the eye on them.
Then he, possessed by Ansem SoD or not, got his hands on the Keyblade of the Hearts of People, which considering it was powered by six hearts of pure light and also had the unique ability to unlock individual hearts should logically be extremely powerful, like second or third to the X-blade.
Back to Soul Eater in CoM and until the end of KH2, it was either stupidly powerful by default considering the people Riku was able to put down with it, or was always a pseudo-KB and was using the power of his heart. That it took so long to transform into a proper one, over a year, is pretty crazy since there's always supposedly one KB for every heart worthy of wielding them. Riku was dealing with his his darkness stuff, but we have seen plenty of dark KB users at this point, and he certainly wasn't too weak to use one since he was able to temporarily take back his original from Sora in KH1 and used Roxas's Oblivion against him during their fight.
Then after spending all that time figuring out how to summon/make Way to Dawn, he just pulls Kairi's KB out from nowhere and hands it off to her like it's nothing.
THEN, after having ownership of WtD for maybe a few months, he lets it get snapped in half and just tosses it to have Yensid make him a new one in a day or two. What? Yeah I know he left it for Riku Replica, but would a broken KB really be that helpful to someone who can presumably still summon a copy of Soul Eater?