In Hinduism, Vashistha was a saint who possessed a divine cow. The cow's offspring could grant whatever its owners wished, which made Vashistha wealthy. This is why the Sanskrit word for "wealthy" is vasistha. This is an apt name for vasisthasana as it can help the practitioner feel abundant in power and confidence in their yoga practice as it requires strong mental focus and balance.
Vasisthasana also assists in opening the anahata (heart) chakra as it opens the chest. This helps the practitioner to feel more receptive to the serenity, love, balance and peace that is all linked to the anahata chakra.
This asana helps prepare practitioners for more advanced arm-balancing poses.