The Kukri is the default melee weapon for the Sniper. It is a large, curved knife. It posseses the default melee damage. This is a better choice to equip for ambushing, as Tribalman's Shiv has lower damage and is better for hit and run tactics, the Shanshasha has lower inital damage and you enemys will have caught on by the time you are damaged enough, the Bushwacka  has a fire damage penalty that is only worth it with Jarate. This the second best weapon generally against spies, the first usually will be the Tribalman's Shiv due to it's bleeding, will cause you to easily see the spy even if s/he is cloaked.