Along with venting extra power from an unstable kyber crystal, the crossguard lightsaber is supposed to maintain the consumer shielded from sneaky blows. It is the identical objective that an actual crossguard serves on an actual broadsword, stopping an opponent from sliding down the blade and slicing at your arms, in addition to stopping you from by accident chopping your self throughout battle.
For as a lot grief because the design bought when it debuted, it arguably makes extra sense than the common, unadorned lightsaber hilt. In “Revenge of the Sith,” Anakin Skywalker defeats Depend Dooku by doing the precise factor the crossguard is designed to forestall: sliding down his opponent’s blade whereas their sabers are locked, slicing off his arms, and leaving him defenseless. That is the one time in mainline Star Wars that we see somebody efficiently pull off a transfer like this, but it surely does not appear laborious to do. Just like the query of why individuals do not quickly flip their lightsabers off after which again on to interrupt locks, this can be a element that is finest not to have a look at too carefully.
It nonetheless appears odd that the crossguard saber did not stay in vogue through the Republic’s last days. The rationale, clearly, is that nobody at Lucasfilm had provide you with it but. If we actually needed to seek out an in-universe clarification, you would argue that the design’s extra cumbersome nature — evident in each Kylo Ren’s preventing type and Cal Kestis’ crossguard saber in “Star Wars Jedi: Survivor” — made it unpopular for the fast-paced preventing kinds of the prequel period.