If one of the steady dungeons is on bonus, you can complete a Mahatma with a single run, making it pretty worthwhile. Otherwise the same rules apply from the Nexus step: Spam “The Bowl of Embers” if you’re running solo to get about 12 light per minute. Run “The Bowl of Embers (Extreme)” if you have a high-level friend willing to two-shot the boss for you.
How to get an ARR (Zodiac) relic weapon in FFXIV
Here’s all the steps to getting your relic weapon from A Realm Reborn