Everything Waheguru has created, has a specific role to play e.g. eye lashes stop the dust from going in the eyes, similarly nostril hair perform the similar function. Facial & head hairs, besides providing unique identity, protect & provide necessary nourishment to the brain. The spiritual aspect & other benefits of hairs are beyond human perception. Therefore, the Gurus strictly advised the Sikhs against cutting hair. Also, looking back in the history, all the Holy persons kept their hair unshorn e.g. Jesus, Mohammed Sahib. Mahatma Budd grew His hair after the spiritual enlightenment.
On the spiritual front, it is also a reminder for a Sikh to keep the mind clear of bad thoughts by constantly remembering Waheguru's Name / virtues
"Kirpan" literally means 'Merciful hand of Waheguru ' which Waheguru uses to deal with the evil. This virtues of Waheguru is inherited in the Khalsa who is Waheguru's reflection of strength to safeguard the weak / innocent and to uphold the justice. The Kirpan is never used as an offensive weapon.
Kirpan is touched to the Karah Prashad (sweet pudding) and the Langar food to make it sacred by first offering to the Waheguru during the Ardas (prayers) before it can be distributed amongst the Sangat (congregation). The process is called "Bhog Launaa".
'Karha' is made of iron symbolizing purity & strength. Its circular shape signifies Waheguru's existence that has no known beginning and end.
Sikhs are not allowed to wear gold Karha since an iron Karha represents equality and humbleness due to its affordability by all the Sikhs irrespective of their monetary status.
Kachhera represents modesty and high moral character. It reminds Sikhs of their moral obligations not to have illicit relationship outside their married life.
A cotton cord/string (Nala) is used to tie the Kachhera around the waist instead of an elastic chord as it provides more secured knot to prevent it from accidentally slipping down.
There are some examples from the history where Sikhs used the long cord to tie down the trouble makers/enemy.
