Why is the symbol of Vernal Equinox ♈? Since the direction of Vernal Equinox lies in the Pisces constellation, why is its symbol Aries? Shouldn't it be ♓ ?

Is this a historical anachronism, only invalidated by axial precession of Earth?
As Wikipedia explains in the article on the Zodiac, the Zodiac was originally developed with the assumption of fixed equinoxes. It is assumed this is because the Babylonians who developed the Zodiac were unaware of the precession of the equinoxes. At that time, about 2500 years ago, the vernal equinox did in fact lie in Aries. For this reason, in astrology, that time is referred to as "the Age of Aries".

Of course, in modern times these astrological concepts are scarcely important to astronomy, and in the few cases where the astronomical symbol for the vernal equinox is used, it is more practical to have a fixed symbol than a changing one.