The Master Sword, also known as the Blade of Evil's Bane, is a legendary blade dating back to ancient times. Originally the Goddess Sword, it was crafted by the goddess Hylia, tempered with the Sacred Flames of the three Golden Goddesses, then blessed with Hylia's own power, granting it the power to repel and vanquish evil, destroy magical barriers, and break curses involving dark magic. It is also an exceptionally good blade in addition to these qualities, being far sharper and lighter than any non-Tinkertech sword, as well as nearly unbreakable.
Normally, this sacred blade could only be wielded by those who were pure of heart and strong of body, repelling those of an evil nature and potentially killing those too weak to draw it - however, your version of the sword lacks either issue, allowing you to wield it with impunity regardless of strength or moral character. Additionally, the Master Sword can, in some cases, be enhanced even further beyond its baseline, such as being further tempered by an expert blacksmith, or through being infused with an outside source of power, for example.