Considering the low damage it deals, it's best to use Hokuto's Bow as a supportive tool to a more powerful weapon, as it will significantly increase the DPS of both weapons and skills.
Since the status effect lasts for 15 seconds and can be re-inflicted when it wears off, Hokuto's Bow is a viable support option for both crowd control and tankier enemies. As it would otherwise occupy a valuable weapon slot, a good option would be Acrobatipack, since its status effect isn't affected by the penalty and it only needs to be applied rarely for support.
It works well with damage-over-time weapons such as Firebrands, Throwing Knife and Alchemic Carbine because the mark effect damage bonus will be fully capitalized on as long as there is even a single damaging status effect on the enemy to constantly apply the damage buff.
Notes
Hokuto's Bow does not benefit from the mutation Ammo
Though the refire time for Hokuto's Bow is 0.5 seconds, the player regains control after 0.25 seconds, resulting in a minimum wait time of 0.25 seconds between the end of one shot and the beginning of the next.
The increased-damage-taken debuff inflicted by this weapon's arrows is applied after the enemy is damaged, provided they survive the attack. As a result, enemies that usually die in one hit, such as Bats and Kamikazes, cannot be used to spread the debuff unless they have been tagged by the death of another marked enemy.
Affixes such as "+80% damage on poisoned targets" apply to the projectile damage but not the mark effect.
Trivia
The head of the arrow in the weapon's icon resembles crosshairs, symbolizing marksmanship.
Hokuto's Bow is a reference to Fist of the North Star, Hokuto meaning North Star or Big Dipper. The line "You don't know it yet, but you're already dead" is a quote from Kenshiro, the anime's main character.
History
0.5: marks can now propagate to all nearby enemies when the marked enemy is killed.
0.7: marks can now propagate to enemies behind walls.
2.1: Scaling changed from Brutality/ Tactics to Tactics.