Tool isn't getting taken from players backpack. Any help? I accept answers!

The error you say attempt to index nil with "Backpack" is because player is sometimes nil, if for example an Accessory's Handle touches the part, it's parent is not the Character but the Accessory so using GetPlayerFromCharacter on it will return nil, you can fix this by checking if player is not nil as the other guy did:

local deBounce = false

local function takeRocket(hit)
	local player = game.Players:GetPlayerFromCharacter(hit.Parent)

	-- This will return if player does not exist
	if not (player) then
		return
	end

	if deBounce == false then
	...

Other issue is that if rocket tool is equipped, it's not in Backpack but in the Character so you should look for the tool in both like this:

local function takeRocket(hit)
	local Character = hit.Parent

	local player = game.Players:GetPlayerFromCharacter(Character)
	
	if deBounce == false then
		deBounce = true
		wait(1)
		local rifle = player.Backpack:FindFirstChild('AssaultRifle') or Character.AssaultRifle
		rifle:Destroy()
		deBounce = false
		...