The Dwarven Barbarian has a Maul in which he crafted, it does 2d10 damage. He has a gauntlet of his god called "Throgren's Right Hand", which adds a +2 enchantment bonus to any weapon he wields using that hand, as well as +2 armor class, he can wield 2 handed melee weapons 1 handed with it, as well as add up to 6 gems into the hand, each one with an added damage bonus once a long rest if he chooses to expend it. He also has crated a helmet from a giant's skull, which grants him advantage on intimidation checks against giants, as well as has a fear effect on giants within 30 feet, Wis save DC 8 + prof mod + Str mod. He has also crafted a tooth necklace from his fallen enemies, it contains teeth from cultists, kobolds, goblins, and now orcs. The necklace is starting to become more of a tooth "chainshirt" with how many teeth it has, and has the same effects towards the cultists, kobolds, goblins, and orcs as the giant's helmet.
The Bard has an outfit which makes him proficient in every save/skill (not tool or vehicle or language), and he gets advantage on those things. It also adds +2 to all of his stats while he wears it. He also has a bastard sword which does 2d8. Both these items combined have use his 3 attunement slots, and give him a daily roulette power which I roll a 1d20 to determine the effects.
The Monk is a changeling, his character backstory is he isn't from this world, or at least he doesn't believe he is. His magical item is an alien alloy sphere which floated through the vast stretches of space and time in search of one worthy to command wear it. Essentially the suit makes a bond with it's bearer, covering them with a protective lair of it's malleable form. It basically turns the Monk into Ironman's Hulkbuster armor, but in all silver. The suit has power points equal to the current total max hit dice of the monk, and certain actions cost a power point. The suit also raises the unarmed strike up a die-grade, and give the monk a ki blast. The monk can expend points to shoot larger ki blasts, really large ki blasts, heal, self destruct, or fly. The suit grants resistance to several types of damage, and immunity to I believe 2 types. However, the monk's land speed is halved, they are vulnerable to electricity, and they can't cast spells or use spell like abilities while in the suit.
What are the artifact rules?
For anyone else who is curious, the world we are playing in is a homebrew. The land we are playing on is extremely high magic. So magic items are semi common, and more powerful items can be made.