Can't help with the wood issue (but I'm sure they would've been using whatever stock blanks were sent to them, and I don't see any reason why the odd chunk of maple wouldn't have gotten through), but the opposing arrows are the customary way of marking that a given item was legitimately sold out of service. The first arrow shows that it was accepted into service, the counterpoised arrow shows it was sold (as opposed to being lost, stolen, etc.)