Black Steel is a high tier weapon, good damage and highest crit rate, but I wouldn't call it the best weapon. I'd say that's the Meat Grinder, not only does it hit 3 times each turn (which basically makes you one-shot nearly every weak enemy in the game) but it has a 100% chance to inflict bleed, which does damage over time based on the enemy's max health, for bosses this can cause them to take damage in the thousands each turn after you hit them once.
Best armor is The Darkness, no special traits really, just really high stats.
Also I'd recommend Hardened Heart accessory to prevent dying from an attack so long as your health is above 1, Leechmonger Ring to give Lifesteal, which synergizes well with the heart and grinder, and Salmonsnake Rune which prevents you from losing limbs to enemy attacks.
Not sure if you can add all those items to a character at the start or not as I'm not a modder, but if you want to start off the game like a total beast those five items would let you overcome most challenges in the game even without the other stat boosts you have in the mod.