Let's 1st understand what these planets represent on their own?

Jupiter - It is the most benefic planet and it represents all the auspicious things like Knowledge, Wisdom, Law, Guru, Spirituality, Religion, Philosophy, Literature, Elderly People and Children etc. For a girl, Jupiter also represents Husband.

Ketu - Just like Rahu, Ketu also represents Illusion as both are ilusionary planets but the difference is that Ketu is also the one who removes the illusion and brings enlightenment. Besides this, Ketu represents Isolation, Separation, Spirituality, Mystical World, Other Dimension means things related to Alien World, also represents Son, Dog, Intuition, Research Ability, Curious Nature, things which we have already achieved in past life and not much concerned to perform in this life. 

House Ruler - Besides these karaka things, Jupiter & Ketu will also rule some houses in your chart and will represent things related to that house. Of course we can't cover conjunctions Ascendant and house wise else it will never be over. So, you have to include those things at the time of interpreting this conjunction. Also, we need to keep in mind all Yogas and Raj-Yogas which their conjunction would be making to completely understand the conjunction. Here, we can only cover meaning as per karakas. 

Meaning of Jupiter-Ketu Conjunction - This shows almost same results as Jupiter-Rahu conjunction (http://astrosaxena.com/juraco) we talked yesterday. The only difference is that Rahu blows things to the outer world and Ketu blows them to the inner being of person. It means that they will be very curious and investigative about different religions/spirituality and they will research a lot on these questions. They may not show but there is a big Mahabharat that is going inside them related to the belief system. They can be on the highest step of ladder of spirituality and will be seen as Spiritual Gurus in world. Don't forget that Ketu is what we have already achieved in past life. So, these people have some sort of expertise on spiritual aspect of life from past life and after sorting out their initial confusion, they are very clear about their spiritual path. Again, they are seekers rather than believers. They will be questioning, researching and investigation all the time. At personal level, as Jupiter represents Wealth, Marriage & Children and Ketu represents separation, they may be detached from family/material life. 

Who will win the Conjunction? - Ketu will. Jupiter is again highly impacted by Ketu who is doubting almost anything. 

Dignity & Strength - 

This conjunction will be good wherever Jupiter is in good dignity because then Ketu will research/investigate about all the good results of Jupiter. So, this conjunction can be good in Aries, Cancer, Leo, Scorpio, Sagittarius and Pisces. 

In other signs, Ketu won't get its perfect spiritual environment so it can feel frustrated in other types of environment and may feel misguided. But then again the basic nature of Ketu in questioning, challenging and researching beliefs & knowledge will be there. 

Hope this helps. Thanks, 

SPB