You have learned the value of using an extra limb to help stabilize yourself in combat.
Benefit(s): As long as you have one free hand (not being used to wield a weapon or hold anything), you take 1d6 less damage from falls and do not fall prone when you take damage from a fall unless you are unconscious. You also gain a +2 bonus to your KAC against grapple and trip attempts when you have a free hand, as well as to Acrobatics and Athletics checks to move in zero-g.
Starfinder Character Operations Manual © 2019, Paizo Inc.; Authors: Alexander Augunas, Kate Baker, Simone Dietzler, Jennifer Dworschack-Kinter, Leo Glass, Sasha Lindley Hall, Amanda Hamon, Vanessa Hoskins, Jenny Jarzabski, Jason Keeley, Lyz Liddell, Luis Loza, Ron Lundeen, Crystal Malarsky, Robert G. McCreary, Conor J. Owens, Joe Pasini, Owen K.C. Stephens, Jason Tondro, and Landon Winkler.