Can you opt not to use a certain (only) close combat weapon in melee?

[Wildcard]

So, the question is if a Space Marine Sergeant has a powerfist, can he choose not to use it, and strike on his own iniative instead? If yes, does he use the bolt pistol (lets assume he has one)?

And if the answer to that is yes, what about Terminator with stormbolter and powerfist, since you cannot use stormbolter as ccw?

Or are you struck with your only melee weapon for the whole game, with benefits and drawbacks?

And a follow up question: If you have multiple close combat weapons (power sword and powerfist), at what point do you choose which one you will be using during combat?

[Wolfshade]

I am unaware of any rule forbidding you from doing so.
On that assumption, you wouldn't use the stormbolter or bolt pistol in close combat per se.
You would use your basic stat line S4 AP -.
It is also worth noting that by electing not to use a peice of wargear arguably you may loose any bonuses for attacks for having multiple close combat weapons.
The choice should be made at the relevant initative values, e.g.
Sarge with Powerfist and Boltpistol,
Fight subpahse, at I4 the sarge can choose to fight at I4 with his boltpistol or wait till I1 and fight with the powerfist.

I would argue that the choice is once per player turn. First round of combat don't use Pfist, 2nd round use Pfist or whatever.

[Tyrendian]

also, a guy with, lets say, a PFist and Lightning Claw, can choose which of his two weapons he wants to use and still get the bonus for using two "special weapons" - nowhere does it say they have to be the same... which would support the notion that you may choose not to make use of wargear you have equipped...

[Ulthwé Guardian]

I was stumped by this question by a friend last Sunday with his Chaos Daemons. It still baffles me :-S

While you're asking if you can forgo one close combat weapon for another. Lets say you your are carrying a single close combat weapon, which has a negative USR e.g. Unwieldy, can you opt not use it for your bare fists, claws, teeth etc...?

[Nabterayl]

So, the question is if a Space Marine Sergeant has a powerfist, can he choose not to use it, and strike on his own iniative instead? If yes, does he use the bolt pistol (lets assume he has one)?

And if the answer to that is yes, what about Terminator with stormbolter and powerfist, since you cannot use stormbolter as ccw?

Or are you struck with your only melee weapon for the whole game, with benefits and drawbacks?

You don't have to use any given Melee weapon, but you do have to use a Melee weapon. Unlike previous editions, 6th edition is quite clear about what Melee weapons any given model is equipped with. The major change from previous editions is that it used to be ambiguous whether (i) "ranged weapons" could be used as basic, non-one-handed CCWs (or even whether there was such a thing as a "ranged weapon" per se), (ii) everybody is assumed to have a basic, non-one-handed CCW, or (iii) not.

In 6th edition the answer is unambiguously (iii), not. You cannot attack with "just your statline;" you must use a Melee weapon. However, if you have nothing that can be used as a Melee weapon (e.g., a model armed with just a lasgun), then you are assumed to have a single SUser AP- Melee weapon (see page 51). Otherwise, you have what is listed on your unit entry and nothing else. Thus:

1. A space marine sergeant with a powerfist and bolt pistol always has two Melee weapons (Sx2 AP2 Melee Specialist Weapon Unwieldy and SUser AP- Melee), and if fighting a vehicle or monstrous creature has three (also S6 AP4 Melee that-only-grants-one-attack). He can choose to use any of his available Melee weapons; he doesn't have to pick the "best."
2. A terminator with a storm bolter and powerfist has only one Melee weapon, since the storm bolter has no Melee profile. Thus, because the terminator must pick a Melee weapon to use, and he only has one to pick from, he must use the powerfist.

And a follow up question: If you have multiple close combat weapons (power sword and powerfist), at what point do you choose which one you will be using during combat?

Strangely, the rulebook never says. We are neither required explicitly (i) to pick weapons at the start of the Assault phase, (ii) at the start of the Fight sub-phase, or (iii) when a model would first have an opportunity to use a weapon. My answer then would be to choose the first time the rules implicitly require you to do so, which is (iii), the first time you have an opportunity to use a weapon. So an I4 model with a power sword and powerfist could wait until I4 to determine which he is using, and at that point would have to choose. But that is just my attempt to be as conservative with the text as possible; I think other, less literal readings are possible.

I was stumped by this question by a friend last Sunday with his Chaos Daemons. It still baffles me :-S

While you're asking if you can forgo one close combat weapon for another. Lets say you your are carrying a single close combat weapon, which has a negative USR e.g. Unwieldy, can you opt not use it for your bare fists, claws, teeth etc...?

Per the above, no. Unless you actually have an item in your unit entry called bare fists, claws, teeth, or something like that (and an accompanying entry somewhere else defining that as some sort of Melee weapon), then you're stuck. Because you have a Melee weapon (albeit an Unwieldy one) explicitly listed, you don't get to claim the basic Melee weapon given to everybody without a Melee weapon listed in their gear. There is no rule allowing you to forego the use of your power klaw, for instance, and headbutt the enemy, even if we can plainly see from your model that you have a head with which to butt. Not even if you're Ghazghkull Thraka, who is famous for headbutting people.

[CarcharodonAstra]

This is one of the things that making me scratch my head.

So i've got a Chaplain with P.Fist and Power weapon/Crozius. He is in CC with 10 Ork Boyz w/ 1 Nob. Can i choose what weapon to use against them?

[Nabterayl]

This is one of the things that making me scratch my head.

So i've got a Chaplain with P.Fist and Power weapon/Crozius. He is in CC with 10 Ork Boyz w/ 1 Nob. Can i choose what weapon to use against them?

Yes, absolutely. You can choose a new weapon each Assault phase. However, you must use the same weapon for all your Attacks in a given Assault phase (if you get two Attacks, you can't make one with the crozius and one with the power fist).

[Wildcard]

Good talk, glad it became clear.

This also means that thunderhammer terminators / nemesis daemonhammer greyknights can't ever strike at iniative 4, they are forever striking at iniative 1.