A similar entry appears in the Wheel of Time Companion confirming the information available in the main story arc.
Author: Atarah al'Norahn
Arwin is a member of the Younglings.
He is about ten years younger than Sevanna.
Arwin is present when three of the Shaido Wise Ones, Sevanna among them, visit the Aes Sedai. After the Wise Ones leave, Arwin comments that he wouldn't mind asking Sevanna to dance; Gawyn replies that she'd probably misunderstand him, since Aiel call battle "the dance". He also says that she'd probably have Arwin's liver for dinner.
Although his name is not mentioned directly during the battle, it is likely that, as a Youngling, Arwin was present at Dumai's Wells. Since he was not mentioned, it is unknown whether or not he survived the battle.
(Reference: Lord of Chaos, Prologue)