I think it's
My Prefix - A+ Place where work to get done, Suffix might send.
The literal 'A', and work can get done in a LABoratory
Specifically, you might get X-rays done for your broken limbs
My Infix - Procedure that can be performed on a tom or some hen.
You might BASTE a (Tom) turkey or (hen) chicken
My Suffix - Place to go with brevity, if wrong way limbs do bend.
If you break a limb, head to the Emergency Room, or ER
My Whole - Feature not representing a faction of darkness, my friend.
ALABASTER is white, the opposite of black/darkness
When finished, type the word that is built with these pieces I lend.
Luke Skywalker says "There is still good in him" regarding Darth Vader, who wears a large, imposing suit of black armor. But what if his good/light side had won...