The concept of balance has no legs and neither does a set of scales
This artifact has a fun story attached to it, too: Originally, Skullclamp was designed to give a +1/+1 buff, but before seeing print the Magic designers thought that such a buff would make Skullclamp too powerful and they changed it to +1/-1
With SCG CON Summer in the books, the current chapter of the Modern format concludes, and a new one will begin with the release of Modern Horizons this Friday
On the other hand, legends in the main set can be designs built around the character independently of other cards to spark new archetypes of decks
Lastly, while it won't keep this thing on the battlefield for long, when a salty opponent does remove it they'll lose five life for their effort
they're entirely subjective