Jonnie, they say great minds think the same, so-as I also thought about adding this weapon, but I think it’s better to list it to spears, since this class of weapons is not very popular and, unlike polearm, does not have a variety(i.e. that spear, that spetum have the same additional features, while pike and billhook are different.
The ability to hold in place should go with a lower probability of being hit( as with daggers) for balance.
I hope devs will listen to your idea and maybe add something similar in the future.