Largely copying from my blog, so, this may be a lot.
This is the Stardust Rod. It's a wand upon many others that are available as equippable weapons in
Little Witch Academia: Chamber of Time. It's said to have power over the very stars in the sky by the Strange Notebook, and is possibly responsible for controlling meteors or comets. This might seem like an outlier at first, but Tier 4 witches aren't exactly something that's rare in the Little Witch Academia verse. In fact, there's been evidence of such even outside of the video game.
The Fountain of Polaris can bestow the powers of the stars onto a worthy witch should they deem them as such. Something Akko and Chariot sought out, but were not granted due to them not being ready for it yet. Yggdrasil has also been shown to hold the stars in place, and is currently the only Tier 4 page in the verse. It is said that in the beginning, witches drew power from the tree until all that was left of them were the Ley Lines. So, back in the Golden Age of Magic, Tier 4 witches were actually quite common.
Witches of the Golden Age were also able to create spaces such as the Horologium Chamber, which is a pocket-dimension containing not only several locations filled with forests, mountains, and deserts, but the Time Void, a space containing an endless sea of stars. It would be safe to assume that they would be the ones behind the creation of artifacts such as the Stardust Rod, which Akko, and Co (Lotte, Jazminka, Amanda, Diana, Constanze and Sucy) are able to use against such enemies like the Time Demon and Molly in her Ghost Witch form, seen below. Since they're able to take attacks from the Stardust Rod and Akko and Co are able to take attacks from them over the course of growing stronger and gaining experience in the Horologium Chamber's dungeons -- JRPG logic for you -- I think it would be fair to say that they should be capable sitting in Tier 4.
But there's still one thing left to cover. The Shiny Rod, which is presumed to be a manifestation of the power of the stars. It was not created, but simply manifested one day to choose a witch worthy of it's power.
There's an interesting tidbit on one of Akko's Chariot Cards that give some insight, albeit misinterpreted by the creator to better glamorize Chariot's image, on what the Rod is actually capable of. The full text reads: "With one swirl of her staff over her head, she gathered light to make the sun and moon. Droplets of magic expanded into the stars and Milky Way." Before manifesting into the world, the Shiny Rod was responsible for bringing about the Milky Way galaxy at it's true power. Both Akko and Shiny Chariot have never fully realized it's power, but it's worth mentioning nonetheless. The Shiny Rod is also capable of breaking the seal on the Grand Triskelion, which was the seed of creation that made Yggdrasil. It is also capable of harnessing it's world-changing magic to warp reality as seen
here. With its power, it can also revive Yggdrasil and spread its magic all across the world. With that, I think it would be
4-A for resurrecting Yggdrasil and
possibly 3-C for creating the Milky Way at it's true power.