Prince of Hearts also translates to "Destroyer of Souls", which can either mean that souls are his target (the way Eridan specialized in destroying hope) or his weapon. Dirk is a master of the latter, fragmenting himself a thousand different ways so that he can properly multitask.

The fact that he's naturally suited to this kind of gambit is not really surprising, as Dave discovered he was naturally suited to time shenanigans as the Knight of Time. Kanaya was pretty clear that the title was related to the competence, though exactly how is less clear (is he the knight because he has the skill or does he have the skill because he's the knight?).

Roxy has to be my favorite part of these updates, however. As upset as she was about her failure to save Jane, the sheer terrified joy of riding the rocket board dominates the scene - and the fact that Roxy has the most endearing expressions in Homestuck to date (even when she was a featureless guardian, in a way) make her even more fun to watch.