I've dug around trying to find any feedback on this weapon, but couldn't find anything substantial. As the highest priced item in the Crystal Shop currently, I'm curious to know if it's worth grinding crystals for?

The short answer is no it's not worth grinding for.

The spork is not meant to be used since it is single use and will kill your pet if you attempt to use it. The purpose of the spork is for steal happy opponents to steal it from you and then time a full blocker right so when they use the spork, they will die and you will be protected by a full blocker. If an opponent steals and uses the spork, it also won't count as single use and will return to your armory after the battle is over. That being said, there are only a couple of opponents it can really be used for. If your pet is strong enough, it also doesn't need to exploit this strategy.

And just to reiterate its single use...meaning it's gone forever once you use it once yourself in battle. That's a lot of grind for 2 seconds of use. Sell those crystals and buy tomes and you get something permanent.

Ooof! I was thinking it was a one-time-per-battle item, not a one-time-ever item. Subetalodge does not mention that it auto-kills you either, thanks for the explanation!

Yeah single use literally means you can only use it once and it's gone. When an item is labeled once per battle, you can use it one time during battle, but it will still be in your armory for the next battle