I had a feeling for past few days. Does Amrit refers to lost wisdom. And yesterday's convo of Rudra and Dadi kind of confirmed that to me. Amrit refers to potent knowledge which in wrong hands can be harmful.
Water from Saraswati Kundh had maginificent healing power. But Rudra's family never tried to understand the reason behind those powers or how that water had healing power. Like many old families they treated it as a boon from Supreme Power. I guess Shivanad wanted to understand the science behind it and knowing the character of Shivanad I guess he wanted to use it for the larger benefit of society.
But what I feel is where Shivanad went wrong was in his search for truth, he never tried to verify his sources or in other words he trusted people blindly without thinking whether it was a good move to share the info with them. This kind of blind trust and knowledge sharing without thinking I guess ended up in the info ending up in wrong hands like Secret society and Swami Balivesh who wanted the knowledge to be omnipotent and to capture power.
If I compare Amrit with Harry Potter it is more like Elder wand which You know Who wanted for which he committed numerous crimes but then it eludes him. Well Dumbledore has his own plans for whom Elder wand should belong
If I take MB it is like the knowledge of using Brahmastra. Knowledge which both Aswathama and Arjuna possessed. But Drona was clever enough not to give the knowledge of withdrawal of Brahmastra to Aswathama because he was sure his son if he had that knowledge would use it to intimidate, oppress, bully people to obey his commands, whereas he gave that knowledge to his disciple Arjuna who he knew would use it only in extreme circumstances either for self defense or for larger good of society.
Coming to modern age it can be compared to knowledge of nuclear technology. On one hand it can give clean energy, have been responsible for path breaking innovations in treatment of cancer treatment and is deployed for many life saving advancement in medicine, in wrong hands any day it can create a Hiroshima or a Nagasakhi.
I feel MK will answer the larger question of the way to attain immortal knowledge is only one. And that is of humility and penance. The most powerful is not the one who uses the knowledge to oppress the other, but is the one who knows he has power but then understands how and when to use it.