Classing it a tool won't prevent wielding it, you can wield a lit torch if you really wanted to.

And a torch gives light whether it's wielded as a weapon or as a tool.
Same should be true for pickaxe - it should grant bonuses either when in tool slot or as a weapon in your right hand.
For both torches and pick axes, no matter your intended use, you still have to hold it in your hand.

Must I repeat myself? The tool slot is there for player convenience and unfortunately the Chaos Orbs grant their bonus when 'equipped' there, which created this precedent. Count yourself lucky in that regard.

"Unfortunately"? It is very fortunate, makes orbs actually useful for something else than giving access to D50 and an occasional emergency heal with water orb (used once in ~10 games in my case).
I don't think it's a precedent, more like lack of consequence or overlooking the rest of items usable in the tool slot.
How do you imagine swimming while holding a shield and a sword in both hands? And yet it's possible, the bonuses are still granted while swimming. Doesn't make sense at all, much more so than pickaxe in tool slot granting the bonuses.
Player convenience or not, the fact remains that in order to use a tool in the tool slot (such as a pick axe) you actually need to hold it in your hand. How is that different from holding it in your hand to kill monsters?
There is no difference at all, hammerhead should give that toughness boost and intrinsics even in tool slot.

I understand what you are saying, but I don't want this to create even more precedents, here in this thread posters are already suggesting that other items with bonusses also grant their bonus while in the tool slot.

Every extra intrinsic, atrribute boost makes a difference in this game. I just don't want to see it balanced too much to the easy side.

Abusing a slot that's main functions are interface and player convenience.

I even suggested an artifact music instrument that adds effects while in the tool slot. If I expect that to be implemented, how can I be so inclined not to accept this implementation? This one just feels too cheap to me in all honesty.

Let's get things clear here:
I'm exclusively talking about Hammerhead - one specific item. It can be argued that since it's an artifact, it can grant mentioned bonuses in tool slot.
At no point in my original post have I suggested to apply this mechanics to any other items, that came later from other people.
That doesn't create a precedence because there are no other items like this and this one is rare enough if you are not a dwarf or whatever race/class can get it via pre/post crowning.
It also grants negligible bonuses overall - 3 points to toughness is less than knife of endurance or bracers of toughness, little enough to be made up for with morgia in most cases.
Fire resistance is easy to come by and stun resistance rarely is truly useful. It's a nice to have intrinsic but nothing OP.
It doesn't abuse the tool slot, no more than any other item there that has a function which requires it to be held in the PC's hand (whips, scourges, torches etc).
Overall it has an infinitesimal impact on difficulty since you have to find it first and it's truly useful only at the beginning, while later people definitely swap it for one of the orbs.
It's not meant to be something to ease things a bit, just something that makes more sense.

The fastest digging pickaxe in the game needs no buff.

It's not getting buffed. It's stats stay exactly the same as always.
Original thread has nothing to do with buffing.

Hammerhead is faster than other pickaxes? That's new to me.

I don't get why this suggestion is receiving this degree of vitriol. I think granting the Hammerhead bonuses while it's in the tool slot is a neat little suggestion that Thomas can take or leave. Throughout most of the game the slot will have a chaos orb in it anyway.

The vitriol is from the hardcore players that can pull a win out of anything. They want the game to get harder so it'll challenge them, unfortunately many of these changes would make the game almost imposable for anyone who isn't well versed on the inner workings of the game. Minor buffs and changes do a lot more to help the newer player than the ones who can quote the DL of major items without looking them up.

I think of a pickaxe as a tool first, as such a special pickaxe should give it's bonus when used for it's intended purpose.

I can say with confidence that no matter how hardcore one would consider oneself to be, the impact of this suggestion on the overall difficulty of the game basically does not exist.

Silfir is right. This is basically entirely a flavor/logical thing and would have almost no impact on gameplay even if it were guaranteed (and it's actually pretty damn rare). (lol at "unfortunately" the Chaos Orbs provide a bonus in the tool slot. if by "unfortunately" you mean "by explicit design")

While I understand Stingray1’s concerns, I doubt this would create much of a precedent, unless TB is going to add massive amounts of artifacts which seem intended more for the tool slot than for wielding them as weapons. As for the RFE itself: I like it because I feel it adds flavor to the game; I would go so far as to suggest two different sets of bonuses, for example:
- when wielded, the current bonuses apply: [+2, +2] {To+3} Fire and stun resistance
- when in the tool slot, these others: [0, +4] {St+3} Sleep and stun resistance
This would make Hammerhead unlike every other artifact in the game; lore-wise, you can attribute it to the powerful rune magic of yore --- which apparently can read your mind and determine whether you are regarding the artifact as a weapon or as a digging tool at the moment; or maybe it has a brawl/goldmine mode switch :-)

I'd suggest that digging with the pickaxe should grant a 10% chance of random item generation when a wall tile is dug out, but OP Guardians of Annoying Difficulties that roam this forum would quickly squash such an impure thought of making ANYTHING easier or more convenient for the player.
They are like ancient jealous and vengeful gods that keep watch over everything and only want to make things infinitely more difficult and tedious, just because it can be done ;)

I'm on your side and even I think that the last suggestion is FAR too overpowered, even .1% would be.

This is a very bad idea and I'm definitely not an OP Guardian of Annoying Difficulties...

That was a joke and a bit over the top so don't take it too seriously ;)