80s Sci-Fi film where alien race agrees to arm transplant to try and kill the bad guy

Question

I am trying to identify a Sci-Fi movie from the 80s. Amongst the 'good guys', there are three identical aliens with a form of telepathy that allows them to synchronise their body movements. They have humanoid bodies, and glow white. They agree to an arm transplant and so an arm is surgically removed from one of the aliens. The arm is then sent as a gift to the bad guy, who transplants the arm as a sort of trophy. Once the arm is attached, or during the surgery, the trio of aliens try to control the arm (using telepathy from elsewhere in the galaxy) in an attempt to cut the bad guy's throat with his newly transplanted arm.

Answer 1

This is likely Battle Beyond the Stars (1980) produced by Roger Corman, borrowing from my answer at Searching for title of 1980s sci-fi movie that reminded me of Star Wars

The farming world Akir is threatened by the tyrannical warlord Sador (John Saxon), who rules the sinister Malmori Empire and, his body parts deteriorating, is capturing and appropriating them from others. Sador's huge dreadnought, the Hammerhead, mounts a "Stellar Converter", a weapon that turns planets into small stars. He demands that the peaceful Akira submit to him when he returns in "seven risings of your red giant", or he will turn his Stellar Converter on their planet. Zed (Jeff Corey), last of the famous Akira Corsairs, is old and nearly blind. He suggests they hire mercenaries to protect their world. Since Akir lacks valuable resources, its people can offer only food and shelter in payment. Unable to go in person, Zed offers his ship for the job if they can find a pilot. The ship is fast and well-armed, but, despite its AI navigation/tactical computer Nell, cannot defeat Sador alone. Shad (Richard Thomas), a young man who has piloted the ship and is well known to Nell, volunteers for the recruiting mission.

....

Later, Shad meets a set of five alien clones who share a group consciousness named Nestor. They admit their life is incredibly dull, since their whole race shares one mind. In order to be entertained, they have sent five members to join Shad's cause. Nestor does not require payment, saying they are completely self-sufficient....

I see Nestor's interrogation scene around an hour and a third into the film on the copy I found online. One of the Nestors specifically says "that facet has ended" after the glowing chainsaw is lowered to harvest his arm, although they then attempt control of the transplanted arm to kill Sador.

Trailer

Found on a list of 11 Movies and TV Shows That Tried to Be Star Wars