Well... I think the Wooden Wrench is a fair enough name, honestly. If it is accepted into the game, Valve could think of something.

As for stats?
First of all, it's wood. Not some heavy @ metal, wood.
+15% firing speed
At the same time.. It's wood. Not some nonflammable metal.
- (2 seconds of afterburn damage will completely destroy the weapon, and it takes 15 seconds to recharge.)
Once again, it's wood, and, personally, I think getting the living heck beaten out of me by wood is far less painful than getting the living heck beaten out of me by metal.
-20% damage
And, of course, it's wood. Last thing I see these days is an engineer whacking some metal contraption with wood. It doesn't do too much, does it?
- (Hitting engineer buildings only adds 20 metal progression)

That's a lot of downsides?
No one's going to use this with those sorts of downsides, right?
Well, there's another thing we should remember... "First of all, it's wood. Not some heavy @ metal, wood."
+20% movement speed while weapon is equipped and +10% when weapon is not equipped. Speed dropoff when moving buildings is negated.




Basically...
+15% firing speed
+20% movement speed while weapon is equipped and +10% when weapon is not equipped. Speed dropoff when moving buildings is negated.
-20% direct damage
- (Hitting engineer buildings only adds 20 metal progression)
- (2 seconds of afterburn damage will completely destroy the weapon, and it takes 15 seconds to recharge.)




I could see some use in this one, as an engineer main.
"+15% firing speed" means that you can quickly heal your buildings and upgrade them (even though only 20 metal is deposited onto the building on hit)

"-snip- movement speed -snip" is extremely useful. As a front-of-the-line engineer, it's just hell when a few things happen.

1) You're repairing your sentry and some big heavy comes around the corner with a medic stuck up his butt.
Solution : Now you can quickly escape with your sentry, 20% movement speed bonus makes you move faster than even the medic.
2) You're off fighting with your widowmaker (that's my shotgun) and some soldier decides he wants to go and hurt your sentry.
Solution : Assuming you don't have the Rescue Ranger, getting to your sentry is a piece of cake. Repairing it (+15% firing speed) is just icing on the cake.

Of course, pyros are a new sort of deep-dug hell with this weapon. Not close to a health kit or (smart) friendly pyro? Tough luck. You're sentry's probably screwed if that's what is being attacked.

And this wrench probably isn't designed for on-the-fly construction, given it takes an extra hit (an extra 1/4 of a second) to upgrade your sentry, which can actually mean a lot if you're setting up at or just after an enemy push.

Overall?
Yes. These stats. I love them.
If valve added this wrench with these stats, I'm pretty sure my eyesight would drop 5 points from sitting at the computer so long, using it.

Comment on stats (and open thinking) below! :)