The Kirpan reminds the Sikh to always be ready to fight against oppression. It is more of a religious than a weapon. It is their cross, their Star of David, their crescent moon. To not let them carry this very religious symbol would be a violation of their constitutional rights.
Myself being a follower of the Islamic faith, what seems to get to me is the fact that countries for example, France, etc... Will ban the women on wearing the Hijab. The Hijab for those that don't know, is a Piece of cloth worn over the head of females to cover up the head and neck area. As a part of modesty. Governments ban Hijabs but ignore the fact that their could be some insane man walking around with a giant dagger is his pocket ready to kill anyone that messes with him. What is more dangerous? The Kirpan, or a harmless piece of cloth used to protect yourself from the eyes of sexually active men out there? Well seems like the Hijab is more dangerous.