
Raksha-bandhan is the festival to revive and relive the love that exists between brother and a sister. The occasion is also known as Rakhi Purnima and falls on the Purnimal that comes after Vyasa Purnima.
Talking about the history of Rakshabandhan, Rani Karnawati during the medieval era, when Rajputs were fighting Muslim invasions, decided to send rakhi to Emperor Humayun. Rakhi at that time meant a spiritual binding & protection of sisters. Emperor Humayun was touched by this gesture& left Chittor immediately.
It is also a belief that Alexander the great's wife sent Rakhi to king Pura or Poras. During the war, he refrained from Alexander.
Such is the power of the string called Rakhi. The string power can also be compared to the umbilical cord that lays a child with the mother before birth. Rakhi is surely the cord that binds a brother to his sister.
However, the auspicious day of love can also be commemorated as the day to create pious resolves, experience ones proximity to God and to salute the rishis. The day can be observed as the day to enhance out love for & faith in the Almighty.
Your sadhaka may be capable of protecting his sister and worldly riches, but saints & Gurus possess the power of protecting the spiritual treasure.
The Sadhaka requires protection from saints & Gurus. This would protect him from losing the spiritual concepts accumulated by him. This is also the reason Raksha Bandhan is known as 'Suraksha Purnima' or 'Protection Purnima'.
As a Sadhaka advances on the path instructed by the Guru, his family and relatives try to pull him back.
The festival of Raksha Bandhan can be best understood by splitting the name in to different alphabets.