harry potter - Why would Charlie Weasley give up his old wand and give it to Ron?

In Harry Potter and the Philosopher's Stone, Chapter 6, Ron says:

You never get anything new either, with five brothers. I've got Bill's old robes, Charlie's old wand and Percy's old rat.

What I don't understand is why Charlie would give up his wand to get a new one. Since the wand chooses its owner, his original wand was already an excellent fit for him, and I seem to recall that a wand grows in power the longer it is in the possession of its owner.

The most common reason we see for wizards getting a new wand is that the old one is broken. But the wand was perfectly intact when Ron had it (before the Whomping Willow incident anyway). And as far as I can tell, there was nothing else deficient about the wand.

So if Charlie had a perfectly good wand that was already in tune with him and would become better as he continued to use it, why would he give it up and give a different wand?

Answer

But the wand was perfectly intact when Ron had it (before the Whomping Willow incident anyway). And as far as I can tell, there was nothing else deficient about the wand.

I wouldn’t quite agree with that.

The very first time we actually see the wand (not when Ron describes it, but a bit later on the same train ride when he tries to turn Scabbers yellow), it’s described thus:

He rummaged around in his trunk and pulled out a very battered-looking wand. It was chipped in places and something white was glinting at the end.

‘Unicorn hair’s nearly poking out. Anyway –’

That doesn’t sound like a wand in mint condition to me. Knowing Charlie’s temper and future job, I can imagine him not being the Cedric Diggory type of guy who’d take brilliant care of his wand and keep it in pristine condition—he’d be more likely to have some fun with it, to the point where it’s in… well, the condition described in the book.

The wand never does work particularly well for Ron, either, even though family ties help hand-me-down wands perform better than non-family wands.

My guess is simply that Charlie’s old wand (perhaps even a hand-me-down for him as well, originally) was getting battered and a bit long in the tooth and wasn’t performing very well for him anymore, so when he got his fancy dragon job in Romania—where a functioning and up-to-speed wand is likely quite crucial, given what he’s working with—he or his parents (or indeed, as Nacht notes in the comment below, his employers) coughed up the Galleons needed to get him a newer one.