If you already have an MLB'd Summer Myuria it might not be better to MLB A2...but it's A2, haha. Even if I had Summer Myuria I'm not sure I'd be able to resist, She's more of an offensive tank than Myuria, but it's up to you.
As for weapons, Beastlord is the only (current) light attribute great sword in Japan, but it's not the end-all best weapon for A2. You'll want to switch between whatever elemental imbues great swords you have (depending on what you're running), and if you don't have one to counter (or the boss doesn't have a weakness) then the event great sword is great for her. All of the event weapons suit the NieR characters great, although you'll need to get hammers to drop to MLB them all since you only get enough to MLB one (and maybe another half of one) with the event rewards/achievements/etc., so choose the one you want more first and then try to grind out more hammers as fast as you can (event ends tonight). I ran the event A LOT yesterday to MLB both accessories and somehow managed to get enough hammers to MLB all three event weapons. They're great for general purposes.
She's my next target too!
