The following is an idea of a "terraria overhaul" style of spear rework you could implement. Since they have stuff like unique sword swings etc with momentum and speed influencing damage with a heavy attack that can finish off foes and is really satisfying or ability to super charge your spells or charge your bow manually and do hover shots etc. you could get ahead and make something that follows:

Add the ability to charge by holding rightclick to get a power thrust that dash you towards the aim and deals amplified damage to all foes hit.
if the spear thrusts once a second it'd take about 2 seconds to charge. If you power thrust a weak point you get the massive damage while also getting some I-frames to negate any cheesey impact damage from the dash while feeling satisfied with further increased and spicy big damage.

Then also add the ability to simply tap and release rightclick before fully charged to quick stab or "flurry" with the spear at a mildly shorter range for less but quicker damage. This is akin to a shortsword attack but directional. This would be a quick, single hit and spammable type of strike good for juggling smaller foes or abusing openings on bosses who might stand still with a barrage of hits.
This could maybe theoretically have a chance (or guarantee) to not consume the weakpoint if you hit it but deals less of a multiplier but still always crit?

Finally, these changes should work on any weapon that is detected to be a normal terraria style spear of some kind, or have a whitelist where you can put spears at your own risk it if they don't auto pick up from mods.