Bat'leths weren't even mentioned in the dialogue exchange between Bashir and Odo. Here's the dialogue here:
Indeed, given Bashir specifically says he doesn't want a firefight at his doorway, they clearly aren't talking about Bat'leths.ODO: I just want you to know I'll be assigning a security team to the Infirmary for your protection.
BASHIR: Thanks, but I'd rather you didn't. I'm going to have wounded people in here. The last thing I need is a team of deputies having a firefight in my doorway.
ODO: I understand. Just do me a favour. Don't count on that blue uniform to protect you. In the heat of battle, Klingons aren't very choosy about their targets. Doctor or no doctor, you might end up having to defend yourself.
BASHIR: Well, hopefully it won't come to that. But if it does, I promise you I'll be ready.
ODO: That's all I ask.
BASHIR: And while we're on the subject, Constable. I'm sure there's more than one Klingon who thinks that slaying a changeling would be worthy of a song or two.
ODO: Doctor, if a Klingon were to kill me, I'd expect nothing less than an entire opera on the subject.
BASHIR: Maybe. I just don't want to have to listen to it. Watch your back.