Shukra Graha or Venus is associated with spiritual ecstasy. This quality is very close to the character of Parashurama as explained by Shri PVR Rao in his video lectures:
Parashurama was born to the sage Jamadagni. Jamadagni had a divine cow
called KamaDhenu. The king KartaVirya wanted the wanted the cow for
himself and took it by force. Parashurama, enraged by this, killed the
king using his axe and killed all the warrior clan that belonged to
the king.
In another incident, Jamadagni asks Parashurama to kill his mother.
His mother, Renuka was a devoted wife and used to go everyday to get
water from the river. One day, a few Gandharvas were visiting the river
and some temptation arose in her. The sage Jamadagni found this out
due to his yogic powers and asked Parashurama to kill her.
Parashurama, being very obedient to his father, went ahead and killed
his mother, without any delay. Being very pleased with this, his
father asked him what he wanted. Parashurama asked for a boon to bring
her mother back to life.
Here is the symbolic meaning explained in the lecture:
Jamadagni represents the burning fire of Sadhana. When the spiritual
fire becomes strong, it gives rise to spiritual ecstasy (Parashurama).
Spiritual ecstasy (Parashurama) can only rise in one, when the
arrogance has been killed and purified. Here, the king KritaViraya,
represents the arrogance born out of brave deeds. When such ecstasy
rises, it kills and purifies and relative temptations arising due to
Maya (which is represented by Parashurama's mother). Also, such
ecstasy, kills and purifies all the kshatriya qualities in one like
revenge, anger etc. (represented by killing the warrior clan of the
king KritaVirya).
Also, the merciless nature of Parashurama, represents the Rajasic nature of Shukra Graha in its dealings.
PS: The above is not a word-to-word translation of the excerpt. For original lecture, see this: https://www.youtube.com/watch?v=1McGPZvC2Uo