While the sword belongs to Halfshell, Snaptrap/Turtler's Beast Wars II counterpart, it's likely just there as a placeholder. The tweet itself, when translated from Japanese, states that everything will be made clear on Friday May 15th at noon, Japanese time (10 pm CST). While the teal hand and the sword are pretty much a confirmation that we're getting God Neptune from Takara Tomy in the Generations Selects line, we'll also likely learn if there will be a recolor of the Nautilator/Lobclaw mold included, as the original toy and cartoon never featured one.
Stay tuned to Seibertron, and we'll bring you official word on Takara's next project as soon as we know!