If quantum spin does not have an absolute axis, just an abstract up or down "direction"; how come magnets have very clear axes that can be rotated granularly into any direction and have their magnetic field rotate with them?

According to the manga that I've read in JOJO part 7.

The Spin (回転, Kaiten, literally "rotation")is a supernatural phenomenon wielded by Gyro Zeppeli and Johnny Joestar and featured in Steel Ball Run. It is a state of perfect or near-perfect rotation which produces a unique form of energy that can be applied for a multitude of uses. The Spin may be considered a counterpart to the Ripplepower featured in the original timeline.

Description

The Spin is a state of rotation defined by its closeness to perfection, that perfection being the Golden Rectangle(黄金長方形, Ōgon Chōhōkei), more specifically the Golden Spiral that is derived from the Rectangle, a mathematically endless spiral and a feature said to be omnipresent in the surrounding nature and a fortiori in works of arts[1]. Unlike the average rotation, the Spin is persistent and produces more rotational energy[1] than it takes to create. That rotational energy is transferred to nearby objects in the form of vibrations[2] and can be wielded for a wide array of purposes.

/r/AskScienceDiscussion Thread