Referring to Useless cross-guard on a lightsaber? fans here should be very familiar with the crossguard debate when Kylo Ren's lightsaber was first revealed. However, we've since proven that those are actually vents for excess energy from Kyle's flawed crystal.
Since then, we've observed a Jedi's lightsaber bearing the same crossguards. In Twilight of the Apprentice, we see Ezra pick up an ancient Jedi lightsaber that ignited fully, including two crossguard blades as stable, controlled beams, before the entire weapon shorted out due to age.
That didn't appear to be vented energy. It looks exactly the same as the main blade, like Anakin/Luke/Finn/Rey's lightsaber's blade. But on that note, Kylo's vented energies look kinda like the flawed main blade too. But then again, if the crystal hadn't been flawed, those side vents would never have been needed (resulting in the classic lightsaber), suggesting the ancient lightsaber's crystal wasn't flawed (given the stable blade), and so the crossguards might have been there for intents different from Kylo's.
Are those (the ancient Jedi lightsaber) really crossguards and not some design with a primarily utility function? If it's really a crossguard, how does it serve as an effective combat component? Does the old discussion over Kylo's now-proven-to-be-not-primarily-a-crossguard hold true here?