Tool not working when given from an equip gui but works when in starter pack?

I assume your script is a local script, it's a typical remote event question.

1.Add a remote event in ReplicatedStorage called BackpackEquip.

2.Add a server script inside ServerScriptService called Event_Listener

Basically what you should do is that you need to connect the server to the client signal.

--server script--
game.ReplicatedStorage.BackpackEquip.OnServerEvent:Connect(
function(plr,toolName)
    if not plr.Character then--If there's no character
        return nil--stop the function
    end

    if toolName then
        --Equip
        if plr.Backpack:FindFirstChild(toolName) then
            plr.Backpack:FindFirstChild(toolName).Parent = plr.Character
        else
            --unknown tool
            warn("Player has no tool called " .. toolName)
        end
    else
        --Dequip if there is no tool whose name is this name.
        local found = plr.Character:FindFirstChildWhichIsA("Tool")
        if found then
            found.Parent = plr.Backpack
        end
    end
end)

Then your local script:

--local script--
local used = false
local desuboru = game.ReplicatedStorage.Attacks.Desuboru

script.Parent.MouseButton1Click:Connect(function()
    if used == false then
        game.ReplicatedStorage.BackpackEquip:FireServer(desuboru.Name)--or just "Desuboru" lol haha
        used = true
    else
        script.Parent.Text = "Equipped"
        wait(1)
        script.Parent.Text = "Equip"
    end
end)

Ohh there some works to change!

P.S. if you want to dequip the tool then just do:

game.ReplicatedStorage.BackpackEquip:FireServer(nil)

Hey so. In order for a tool to clone to the server, you will have to fire a RemoteEvent. Your code should resemble something like this:

--LOCAL SCRIPT

local used = false
local desuboru = game.ReplicatedStorage.Attacks.Desuboru
local remoteEvent = Instance.new("RemoteEvent")
remoteEvent.Name = "ToolGiver"
remoteEvent.Parent = game.ReplicatedStorage

    script.Parent.MouseButton1Click:Connect(function()
        if used == false then
           remoteEvent:FireServer("Equipped")
            used = true
        script.Parent.Text = "Equipped"
        else


            script.Parent.Text = "Equip"
        remoteEvent:FireServer("Unequipped")
        used = false
        end
    end)

:

-- SERVER SCRIPT IN SERVERSCRIPTSERVICE

game.ReplicatedStorage["ToolGiver"].OnServerEvent:Connect(function(plr, value)
    if value == "Equipped" then
        clone = game.ReplicatedStorage.Attacks.Desuboru:Clone()
        clone.Parent = plr.Backpack
    else
        plr.Backpack.Desuboru:Destroy()
    end
end)

Hope this helped. Trust me I know how annoying FE can be some times. xD