SPOILERS! Please proceed with caution!
According to Making Star Wars, apparently, Luke has three pieces of gear with him on Ach-To which is a compass, an orange backpack and a walking stick with what seems like a cattle prod on the end of it that “looks like something you would just casually zap a pest with”. It clips onto his belt where his lightsaber would normally go.
The backpack is plain and has a knife inside with a mesh water bottle holder.
The compass is described as being “a box with a blue marble-like orb on the top. I believe Luke Skywalker moves his hand over the blue orb and the box opens up to reveal the compass inside the box. The interior of the box has metallic dials with Aurebesh writing inside denoting some ‘space’ version of North, South, East, and West with a needle to point the way.”
These things may or may not have a huge focus in the film, as Luke has had a backpack before while training with Yoda on Dagobah
“There is a rumor that near the end of the film, Luke is going for Snoke and Rey is going for Kylo. I asked the person that believes this to be true if they have an encounter in the film and they didn’t know for sure.”
This may be the fight on Ach-To that we’ve heard previous spy reports about with Luke force-pushing some of the Knights of Ren off of the cliff and then taking on the rest. It also might not be. The previous reports list Kylo and the Knights of Ren squaring off against Luke and Rey but the reports never mention Snoke.
My personal theory is that the battle will play out the way it did in the spy reports and after all of the Knights of Ren are killed (either by Luke or by Kylo himself) and then Snoke will make an appearance and take on Luke while Rey fights Kylo Ren. We will then have master vs. master and apprentice vs. apprentice.
Source: Making Star Wars
R.I.P. Chris Cornell