Let’s look at important things here –
Mars - Mars represents our will power, courage, ability to take actions, aggressive nature, anger, our fighting ability, brother, male friends, a boy friend for a girl, a soldier, an athlete and real estate etc.
Vishakha - Vishakha is nakshatra of counselors and guides. It is also nakshatra of split or partition or different direction. For more information on Vishakha Nakshatra, please check this link - https://www.astrosaxena.com/vishnaksh.
Libra - As Vishakha is a part of Libra, Libra sign and its representations also become important. Libra is the 7th sign of Zodiac Belt, hence it represents the energy and things related with 7th house of horoscope, i.e. Market Place, Business, Partnerships, Relations etc. Libra is sign of Balance, i.e. striking the Balance between 2 parties/ideologies or even at personal level between our own dilemmas. It is sign of Peace and Diplomacy. And this is what we are seriously looking for after the conflicts and disagreements of Virgo, i.e. Peace to prevail. At personal level, Libra is seen as sign of Relationships. Libra is consisted of 2 and half Nakshatra named Chitra, Swati and Vishakha. Libra's lord is Venus only.
Scorpio - As Vishakha is a part of Scorpio too, Scorpio sign and its representations also become important. Scorpio is the 8th sign of zodiac belt, hence it represents the things and energy related with 8th house of horoscope like Sudden Events, Secrecy, Dark World, Occult Science, Research, Inheritance, Serving Others, Taxes etc. Besides these things sign of Scorpio also represent transformation, means changing the whole nature upside down. This is one sign which is favorite of every Astrologer, because it has maximum secrets, so every astrologer gets maximum scope of researching. This is sign about which no one can tell with precision that what will happen to the planets in it, as it is sign of secrecy itself. Wherever Scorpio falls in your chart, you may have had biggest challenges in making things related with that house more stable. Scorpio is also one of those unique signs which has 2 rulers, i.e. Mars and Ketu. In Western Astrology, Pluto also co-rules Scorpio. All this makes Scorpio a chaotic sign. Scorpio consists of next set of 2 and half nakshatras, i.e. Vishakha, Anuradha and Jyeshtha.
Jupiter - As Jupiter rules Vishakha, Jupiter's position and dignity is important to know about the overall functioning of any planet in Vishakha.
Venus - As Venus rules Libra, Venus position and dignity is important to know about the overall functioning of any planet in Vishakha/Libra.
Mars-Ketu - As Mars-Ketu rules Scorpio, Venus position and dignity is important to know about the overall functioning of any planet in Vishakha/Scorpio.
Houses Involved – Also, we can’t afford to forget the houses involved as a planet can be ruling different houses and sitting in different house for every person as per ascendant and planet’s position. To know overall affect, we have to consider the houses involved as those areas of life are being impacted.
Interpretation of Mars in Vishakha Nakshatra – Now, actions and energy of Mars is coming within the realm of Vishakha which is represented by forked branches. These forked branches represent different directions or split paths. So, when Mars is in Vishakha nakshatra, 1st of all in initial life, person can have lots of confusion about where he should put his actions and he may have to always choose between two separate or totally opposite paths of actions. As they grow-up, it may happen that in different times in their career, they may follow different fields of career. Like, they can switch from job to business or vice-versa. As Vishakha is nakshatra of teachers or counselors due to rulership of Jupiter, they can act as coach, guide or counselors. In Libra section, they can be a relationship counselor or lawyer and in Scorpio section,it can be counselling in occult matters. Good thing about this Mars position is dignity. Not only Mars is in nakshatra of best friend Jupiter but Libra is ruled by Venus which is neutral to Mars and Scorpio is ruled by Mars itself. Hence, we can expect overall good results.
Role of Jupiter – Jupiter placement is important to guide Mars in right direction, being Vishakha's lord.
Role of Venus - Likewise, Venus placement is important to guide Mars in right direction, being Libra lord.
Role of Mars-Ketu - As Mars will be in own sign, being Scorpio lord, we need not to see Mars position separately.
Other Factors – And of course, we need to consider conjunction, aspects, house lordship, house position and dashas etc to know the exact results of Mars in Vishakha. So, we always need to take a holistic view of chart rather than just 1 planetary position.
Conclusion – So, this is how I see Mars in Vishakha can work in a chart.
Hope this helps. Please post any comment or query you may have.