Metatron is a super heavy burst damage character. She has fair attack for an SSR, can give herself a stacking +burst damage buff, has a +40% attack buff (sadly B frame, well, at least it's better than A) and can start the battle with a Burst attack.
Put her as the last person in your party and start every fight with a Burst from Metatron. Heck, since you have Sol, use Arthur too. Start the battle with your first Hime having 30+ Burst after turn1. Though, this way, I guess you can't debuff for -40 Def... well, this way is more fun even if it's inefficient.
Anyway, the good side of Light is that you can use it in every single event. Light has no weaknesses. Also, you have the strongest core of Light for the next... seven months? Metatron is the only heavy hitter for ages, and Sol is the cornerstone of any Light team (or any team, heh).
The bad side of Light is... now that Phoenix events are gone, there won't be a +Light elemental Eidolon for you for at least 11 months. That means you're entirely relying on other people giving you Phoenix. Also, while Light has lots of excellent SSRs, they're all focused on utility rather than pure damage. And even with all that utility, they don't focus on debuffs, which is a really bad thing.
Still, if I were you, I'd use that account. It's a very good start, with both heals and damage output.