I'm at the Dragon Cave and have a saved file at a pile of treasure and doing lots of reloading to get the best possible weapons.

After lots of trials and reloading and zzz... I have managed to get the following (in 2 separate files):

Weapon 1
Noxious Bardiche
to Hit Modifier: None
Physical Damage: 4-16
Elemental Damage: +32 Poison


Weapon 2
Obsidian Bardiche
to Hit Modifier: +50
Physical Damage: 4-16
Elemental Damage: None


Which one is the better one to use?

For the Noxious Bardiche, I would think that the total damage normally will be 36-48 (4-16 base dmg plus +32 poison).

For the Obsidian Bardiche, honestly have no idea how the "to Hit Modifier" works and how to compute the total possible damage. Most importantly, if I am dealing with a monster that is immune to physical damage, does it mean that it will hit nothing?

Obsidian weapons are the best. Elemental weapons are good for doing damage versus monsters immune to physical damage like the ghosts in Winterkill (obsidian weapons won't work there), since such monsters are rare the obsidian weapon is much better.

It's harder to get a noxious weapon than an obsidian weapon, but I wouldn't bother carrying elemental weapons around and just use magic.

Obsidian grants +50 to damage and +10 to hit unless you modified your game.

Don't bother with reloading for loot, you don't need it and at the end you'll have found more than enough obsidian weapons anyway.

To Hit modifier just adds to your chance of hitting the monster, at least that's how it is in MM6 and the later games.

Obsidian Weapons,nothing is better than these.