How much Military force you would need for others forces to stay away from You?
We know GB explicitly said Kaido alone was the deterrent / keeping enemies from attacking Wano which includes the likes of Prime WB and Shanks
But Mihawk apparently isn't that level and he even requested for more manpowers.
I mean you should also take the public image of a nation's leader into consideration. Kaido was a goddamn dragon, Most soldiers of any organization would be scared shitless if they were told they had to go and fight a dragon that "
it is said" to be the strongest creature alive and has the highest bounty amongst any pirates alive.
On the other hand, although World's strongest swordsman is a pretty scary title, Mihawk himself is a pretty laid-back dude and has been on the side of the Marines for a long time so they know his personality.