Well as someone SL300 and has everything you’re probably aware every area and boss have their own unique damage types/move sets/immunities. With that knowledge, there is no true Meta-build for literally everything. Some weapons that would shred a certain boss will be a useful as a butter knife in others.

The only real question is how good is the player? Even with a butter knife, a man can slay any god in Dark Souls.

If you’re friend needs a starting build to work off of, I would suggest setting him up as a mage (int), grabbing the long sword and inbune it with fire (fire long sword), and build off that. That was my starting build, made it through the game using magic and the fire long sword myself. (Any of the soul arrows + soul spear for the spells).