Functionally it should work like a dagger (does piercing and slashing damage, 1d4) but is ineffective thrown. You never get a bonus to hit from your ability scores, as this is an awkward weapon. You get other benefits.
+1 to open doors that swing toward you, using it much like a prybar.
+1 to your strength calculations for how much you can carry when you're hauling it with a hook.
+1 to your check to climb or keep your handhold under duress.
On a crit you do no additional damage but do grapple your target.
If you put a big hook on the end of a pole it only comes with the crit benefit.
If you put one on the end of a chain or rope it can act as a grappling hook, conferring both the climb benefit and the crit benefit.
It's also the kind of tool that most farms and any settlements of real size can provide, repair, or replace. Squatfuck of Nowhere can't scare up a smith to put your sword back together. Anybody you talk to has one of these in the barn, though.