Mercury rules 7th and 10th house is in 1st house in Sagittarius

As a Jyotish astrologer, I can tell you that having Mercury in the 1st house of a person's horoscope in Sagittarius sign can have a significant impact on their personality and mannerisms.

Mercury represents communication, intellect, and reasoning abilities, while the 1st house represents one's personality, appearance, and aura. Sagittarius sign signifies higher learning, philosophy, and optimism.

Individuals with this placement are generally very articulate, eloquent, and possess a charming persona that attracts people. They have a keen interest in education, higher learning, and philosophical theories. They are talented at expressing their views and opinions in a way that is impressive and intellectual.

However, they can also come across as restless, impulsive, and overly optimistic at times. They may also have a tendency to be rash in decision making, and may jump to conclusions before analyzing things in detail.

Overall, with this placement, individuals are blessed with excellent communication skills, bright intelligence, and a learning attitude. They can use their intellect to make a positive impact in their lives and the lives of people around them.