The duel wielding feat progression doesn’t work for all characters.
Some concepts will want to wield a light off hand weapon for style, such as a main gauche or wakizashi. Other characters who duel wield will be build around finesse weapons and may prefer a to hold light weapons in both hands.
With the Dual Wielding feat as a prerequisite for Two-Weapon Strike, a character who doesn’t want to a heavier weapon offhanded must take Dual Wielding for no benefit to get to Two-Weapon Strike.
I think it would serve character buidling better if the feats didn’t require each other or the order of the feats were reversed. Either way would serve a greater variety of character builds.
Tangetally related, it's nice to see the katana with its own rules. Having it a finesse weapon is appropriate, but it's missing one important detail.
If the katana is on the weapon list there should be a way to duel wield a katana and wakizashi. Real katanas are hand-and-a-half. Katanas, like the bastard sword, and should be versitile. If simply adding versitile and 1d10/1d8 damage makes the katana too powerful compared to the bastard sword, this could require a katana weapon style feat.