
Koi Eokei |

@BigNorseWolf
I like your logic. That's I've ruled it with target: self wands. I'm almost willing to use a d% to decide where the wand faces, it points somewhere. I'm using the argument the description doesn't support its stringent requirement for use.
A wand is a thin baton that contains a single spell of 4th level or lower. A wand has 50 charges when created—each charge allows the use of the wand's spell one time. A wand that runs out of charges is just a stick. ... A wand is 6 to 12 inches long, 1/4 inch thick, and weighs no more than 1 ounce. Most wands are wood, but some are bone, metal, or even crystal.
"6 inches!" It barely fits in my hand! Let alone points.
ba·ton
/bəˈtän/
noun
a thin stick used by a conductor to direct an orchestra or choir.
synonyms: stick, rod, staff, wand
"the conductor's baton"
•a short stick or tube passed from runner to runner in a relay race.
•a long stick carried and twirled by a drum major
It doesn't say it has a point. Doesn't say how it points. It points where I say it points. Period.
FAQ

Raezial the Thamendaemon |

This is a rare case because you are usually grappled for a round before. Ring pinned.
If you're already holding that wand when grappled, it should never get to pin.What creature in RotRL goes straight to pin?
and he retrieved it while grappled the previous round (which is a full round action)

Azothath |
this is a point where sensibility and rules collide making a thin grey area.
For: By RAW you can do it. Mainly because there's nothing saying you can't and a specific exclusions (wands and grapple) that says you can. That's a strong 'for' argument. Sure, it makes casters with wands very slippery.
Against: Descriptive text and fairness kinda argue that pinned means you can't move. GMs don't want to deny a combat type their joy at pinning a caster. I'd point out that pinned does not make the pinned subject helpless, a fine point but rather valid. Either way, if a GM wants to deny wand use or call for a die roll, that is just them responding to the descriptive text and a sense of fairness or combat bias.
If a GM states that you cannot use a wand in a pin as it is casting a spell, then pearls of power work with wands.
Can you activate a ring of the ram while grappled? What about a Cloak of the Dark Tapestry or Cape of the Mountebank?... I think you see my point.
the debate can be avoided. Simply suggest that the attacker perform a disarm on the first cycle. This puts the wand on the ground or in the attacker's hand.
activating a spring-loaded wrist sheath (with a wand) will be another issue. That puts a wand in a caster's hand as a swift action. I always suggest a character buy two and put a defense wand in one, if not in both.
*sigh* so many contingent issues. UMD. Can this be done in a pin to activate a wand?...