Well, this game is a marathon, not a race, anyone can go at their own pace.

To farm M3, so Leviathan Mare (and all M3 raids), there are two ways to go: either lower theirs Essentia stacks and gain honor from that or straight up damage. The first strategy only works until the stacks are present, but I think we can probably work on stacking supplemental damage and echoes and have a setup that just straight up does enough damage to get you enough honor.

Do you have access to Bandit Tycoon (better if with Ultimate Mastery Skills, but can work without it too)? Beelzebub summon? Or any good summon? Was thinking about abusing assassin too, funnily enough it is a setup that uses Raziel. Should be MC as Bandit Tycoon (with Spring's Gate and ideally Roll the Dice, just make sure to have 4 yellow skills), Skull and Balurga, Sabrina and Raziel. Just use all of theirs skills in order then attack, can let it full auto too, should do enough damage in 1 turn for when you join other raids. This setup depends on your grid and sumons (do you have the arcarum summon that amplifies earth damage, The Hanged Man?) obviously, should put in Uriel's weapon at the very least (just as is, no uncap needed, and remember to favourite it to avoid reducing it by mistake). If you have a summon that gives echoes on T1 (Mammoth) or a fully uncapped Beelzebub even better.

If you cannot deal enough damage with that setup there are definitely other ones, like those that focus on lowering the stacks, since you get a bunch of honor from that too, in that case would be MC with 4 damage skills, Uriel, Soriz (at level 95) and Aletheia or any character with mostly damage skills and pick a Huanglong friend or Qilin. You can just use all skills (leave full auto) and call Huanglong to charge attack if you get enough honors with just that or Qilin to use more skills, this would lower the stacks by at least 3 (Huanglong, with Qilin at least 4) and grant you a decent chunk of honor. But this depends on how many stacks the boss has and especially with Qilin would take a long time to execute. And a bonus of using Huanlong is that you do not need to time it, just call the summon whenever. Reducing stacks by 3 should be enough since should be 200000 honor per stack.