The concept of parrying relies on redirecting the enemy attack, not on stopping it dead in it's tracks.
You can parry a sword with a wooden butter knife if you're skilled enough.

Additionally, for the sake of balance and retaining the spirit of the TT, if you can't kill a fist user during their wind-up(p-fist always goes last, has to survive enemy attacks to even get a chance at hitting them), then something else has to exist to keep things balanced: namely, the ability to parry the p-fist.

Remember, the LP you pay for a p-fist isn't there to cover being the best melee, it's the "can punch tanks" tax.

If we're talking logic and game balance, let me join in.

Since the FREE Tactical, Fire Dragon, Swooping Hawk, Shoota, Dire Avenger Knife can totally shut down all incoming melee damage from 300 to 600 LP melee weapons for 2 to 4 clangs, I propose that all Pistols in game be priced as FREE for melee archetypes and that the Pistol provides 100% immunity to all incoming ranged damage via "clanging" vs all incoming ranged fire for 2 to 4 clangs.

Seems only fair. If you're fine with the logic behind a FREE weapon providing 100% immunity to all incoming melee damage for 2 to 6 seconds then you should be totally fine with a FREE weapon(Pistol) providing 100% immunity to all incoming ranged damage for 2 to 6 seconds. If not you're a total hypocrite.

That's the knife in a nutshell. FREE and provides the equivalent of a Rosarius or Personal Force Field that makes the bearer immune to all incoming melee damage for several seconds.

If the knife can provide such amazing invulnerability vs melee attacks why cant the Bolt Pistol provide the same unimaginable invulnerability for the same duration? Furthermore why is the knife FREE and the Bolt Pistol costs melee archetypes 50LP?

Just letting you know, A heavy attack against orks is unblockable.. Sometimes. I do like it being unblockable and you can roll out of the way with plenty of time, but then again it should be blockable, hard to side on this one. Haven't figured it out fully yet, but it seems on some weapons if they start quick attacking you it will not do anything and the heavy attack will just go straight through. Dbash however does stop a PF heavy, sometimes. This is all against orks btw. I'm slowly figuring it all out, but man weird shit happens with PF melee. Sorry to the orks last night who followed the proper melee mechanics, and die to big Fist to the face.

And this, happens with every weapon. Any weapon's heavy can be blocked with a light attack. And if the light attack happens during the last part of a heavy's animation, it will clang and not counter.

Are you actually this stupid, or just pretending?
Rifle lets you shoot at dudes.
Pistol lets you shoot at dudes.
Both do the same exact things at different magnitudes, just like how a knife can clang in melee(although at a disadvantage) like any other melee weapon.
The knife does not grant you any immunity, it lets you participate in the melee system(the system itself might be busted, but that's a separate issue).

Because what you see as the LP cost of items is not their total LP value.

You gain about 5% additional durability per 100 LP invested into it(it varies slightly class to class).
That means that your baseline durability is worth about 2000 LP, before you even invest into a 10LP trinket.
The same applies to guns: what you see as a oLP or a 600LP cost, is the tip of an ~2000 LP invested into all of your weapons before you even get any say on how it is distributed.