Feel like I've hit a wall

[Its Almost Harvesting Season]

I've explored pretty much the entirely of the map that I can access. I'm 99% sure I've found all secret walls and such, and I am near what appears to the first of 3 big monsters. I tried to fight it but found myself vastly underpowered but now I'm left with nothing to do but grind.

As far as I can tell, I've defeated all the fixed monsters that upgrade level cap, but haven't found anymore of those roaming centaur looking monsters... Max level is 44, is this going to be enough? Do I just have to grind to 44? I'm just unsure because nothing I did seemed to do anything reliably against the boss. Fire never worked, air raid didn't work, guns didn't work, slashing didn't work, blunt weapons didn't work, and my healers can't heal/revive people with the resources I'm generating each turn. The only thing I can conclude is a stat difference because this game doesn't really offer any info on attack/defense.

Any advice on this?

[winter_melon]

The game's damage calculations aren't really explained, but having beaten the game I can say anecdotally that it often feels like there's a threshold below which you do almost no damage versus a given monster at your current level/equipment, and above which you do REAL DAMAGE. Conversely, stacking a few Defense up abilities on your tank or teammates can really make the difference between surviving a round of enemy attacks or straight up dying.

The "Base Attack" value is significantly more important than the "Number of Attacks" stat as a result. On top of that, every weapon has one stat listed for "additional power" and it'll be something like "Melee (20%)", and that stat is the scaling stat for damage. You want to pay attention to the stats which are used for reliability so that your attacks don't bounce off or miss, and then also for the stat for power scaling. Every equipped weapon should make use of three good stats on each character. For the same reason, things which give bonus to attack (e.g. Dual Wielding, Aim, etc.) are often significant bonuses. Because other damage types also involve attack power (e.g. a blade which causes Bleed will deal its attack damage and then apply an amount of Bleed based on the damage dealt), attack power is overwhelmingly important.

Weapon Modifying costs the same amount of materials regardless of weapon rarity, with the real challenge being finding enough duplicates of rarer weapons. I seldom truly NEEDED to use this, but sometimes it can help put you over the top.

Aggro management is important because against bosses which you can't burst down in one or two rounds, it can be really advantageous to NOT deal maximum damage each turn. The reason for this is that if your damage dealers are building more aggro than your tank can generate through things like Advance Guard and Roar, your tank will not be able to tank, and your damage dealers will die. It seems like it'd be suboptimal to cut your DPS drastically, but it actually can have huge benefits!

One more thing I forgot, some weapons/attacks have the trait of dealing multiple attacks to each target. I don't just mean when it says "7 hits!" but it will do something like one attack dealing 7 hits (or however many) and then another attack doing some other number of hits. The Buckshot abilities for instance often seem to do this.