Then don’t. You can continue denying common sense. But if someone threatens to assault you with a skateboard, bare hand or an item from your desk, then will intuitively discover the difference.
My normal desktop items could break skulls too, I'm pretty sure. And the pens, oof...
If you use an item in a manner that can reliably kill people then you use a deadly weapon even if it wasn't intended to be a deadly weapon. Is a pair of scissors a deadly weapon? Yes. Is a heavy hard blunt object (like a statue) a deadly weapon? Yes.
It's not productive to argue about definitions, even if they don't make sense to me. My intent wasn't a semantics argument.
I'm not saying it's right, I'm just offering my observations of precedent.
> “Dangerous weapon" means any firearm, whether loaded or unloaded; any device designed as a weapon and capable of producing death or great bodily harm; any ligature or other instrumentality used on the throat, neck, nose, or mouth of another person to impede, partially or completely, breathing or circulation of blood; any electric weapon, as defined in s. 941.295 (1c) (a); or any other device or instrumentality which, in the manner it is used or intended to be used, is calculated or likely to produce death or great bodily harm.
I would say a skateboard, wielded as a weapon, is likely to produce death or great bodily harm. Getting hit in the head with a skateboard even once seems likely to cause a concussion or maybe even internal bleeding.
You probably do have a good number of items that could be classified as deadly weapons on your desk, depending on how they were used.