Originally posted by RobtardRob is right, you have to have some intelligence to not have to be told explicitly when someone is holding back. Thor has always tried to reason with Loki...he loves him as a brother.
His speech about brotherhood, family and trying yet once again to get Loki to see the error of this ways through reason. Which coincidentally ended right after Loki sneak-stabs Thor and Thor immediately kicks Loki's ass and Loki has to flee. That.You don't really think a hammer-less wounded Thor is more formidable than a Mjolnir wielding unwounded Thor, do you?