Starting on a multiplayer server was the problem in this story.
Multiplayer in general is not really a good way to start playing any game; you oftentimes run into hackers, duped items, or over-saturated economies if the game has one.
I'm sure you know this now, but handing someone an Excalibur and Adamantite Armor doesn't teach them anything about how that armor was gotten, how houses are built, how to navigate the world without such things or even "wtf is going on?".
That's why I start every game I buy in Singleplayer, first assuming the game has said single-player mode. That way, I don't have other people ruining the learning experience for me (trolling, griefing, or unintentional like the sword/armor in your example).