Why won't this zombie damage cool down script work?

Its almost as if the wait(2) is invisible. I posted the same question yesterday and got things about debounces but none of the solutions worked. Please help. I'm not that knowledgeable, but my hypothesis is that it is waiting wait(2), but it is constantly searching for hum so the code is running constantly and dealing damage constantly. My code:

local rarm = script.Parent:FindFirstChild("RightUpperArm")
local larm = script.Parent:FindFirstChild("LeftUpperArm")

function dmg(hit)
	if hit.Parent ~= nil then
		local hum = hit.Parent:findFirstChild("Humanoid")
		while hum ~= nil do
			print("phase1")
			hum.Health = hum.Health -10
			print("phase2")
			wait (2)
			if hum ~= true then
			break
				
			end 
		end
	end
end


rarm.Touched:connect(dmg)
larm.Touched:connect(dmg)

I haven't coded using Lua in a while, but I'm fairly sure you are using the debounce incorrectly, it might look like this:

local rarm = script.Parent:FindFirstChild("RightUpperArm")
local larm = script.Parent:FindFirstChild("LeftUpperArm")
canDmg = true;

function dmg(hit)
    if hit.Parent ~= nil then
        local hum = hit.Parent:findFirstChild("Humanoid")
        while hum ~= nil do
            print("phase1")
			if canDmg then
				hum.Health = hum.Health -10
				canDmg = false;
				wait(2)
				canDmg = true;
			end
            print("phase2")
            if hum ~= true then
            break

            end 
        end
    end
end


rarm.Touched:connect(dmg)
larm.Touched:connect(dmg)