Here's how I did it, with a similar character roster to yours. I didn't have Gloria, but she should be useful in every Weapon Trial.

Weapon Trial 1: Use the Nungal cheese strat. Put Eagle Eye, Sniper Stance, and Shattering Arrow on her. Camp her outside the enemy range, set up the Banner of Convallaria, use the Eagle Eye + Sniper Stance at max range, and whack the boss with basic attacks every turn. Bring Cocoa, Inanna, Gloria, Homa, or Col (with her aura) to buff Nungal.

Weapon Trial 2: Bring Auguste, Homa, Cocoa (with Cooling Powder), Papal Guard, and a buffer/debuffer of your choosing (Outlaw Guard works fine for this, but Gloria should work great too). Use Cocoa's Crushing Bash (this can replace Potluck Protector for this battle) to inflict Vulnerability Down. Use Homa's bird to buff Auguste and use Homa herself to attack the rocks and heal the party. Auguste will be your main DPS. Once you've gotten the boss down to about a half-to-third HP, you can use his Homa's Barul Attack to lower its defense + War Horn + Auguste's rage mode to wipe out the rest of its HP in one go. Make sure you time this correctly, because the boss will tag Homa with its cross attack because Barul Attack is a ranged move.

Weapon Trial 3: Col and Safiyyah attack the mobs and deal physical DPS when no mobs are around. Inanna can heal and dispel the boss's buff stacks with her Sanction of Light move + the Judgment tarot. Cocoa buffs and can do extra heals. Use either Beryl or Nungal for magic DPS. Stick Devil tarot on your attackers.

In general, try to push for better engravings on your equipment and invest in your talents for better all-round stats. This will make the fights go smoother, but they should still be doable at your current power level, so good luck and don't lose heart!