Hello. I've been playing for a few weeks and I wanted to know what arcanes are the best/must have for most frames/weapon builds. So far I've been able to get Molt Augmented and Primary Merciless. I know about Energize but its super expensive for me.
Assuming you have access to the location you get Molt Augmented from normally and you didn't just buy it with plat (though that is a valid option, I suppose), good arcanes to pick up from the same location are Molt Vigor, Emergence Savior, Emergence Dissipate, Eternal Onslaught, and Cascadia Flare. Slightly situationally more useful (though still good pickups) are Molt Efficiency and Arcane Blessing.
Elsewhere, good arcanes to pick up are Secondary Merciless, Primary & Secondary Dexterity, as well as Primary & Secondary Deadhead. Merciless is what you'll likely be using for most weapons, but Dexterity is nice if you plan to use your melee a lot and the Deadheads are great for specific weapons, especially since the +headshot bonus is a flat amount, meaning it also gives a multi to weapons that ordinarily can't headshot (i.e most AOE weapons of any kind). Again, not a universal slot, but it's good to have the option.
It would also be a wise idea to pick up Secondary Encumber from Otak, and if you don't plan on getting Energize anytime soon, even just a single copy which is perfectly functional, then Arcane Steadfast may be worth the grind.
I rushed to do the whole story and unlock steel path/arbitrations so i have access to most stuff atm. I'll check out and farm those arcanes that you mentioned, thanks!!
I've been playing like 4 hours a day since I restarted in March, originally I only managed to beat the first 4 planets, I'm now mr20 something and have the same as above unlocked. But my main motivation was MR rather than content, playing new weapons and frames at low Mr feels so slow and bad. Once I hit Mr 16 (aka everything unlocked) I blasted through all content except eidolons, open world and railjack.