The way I'm going to review this card is by re-interpreting the text into three separate texts, one for each of the outcomes from success (every weapon does the same thing when you fail, so that's an un-necessary consideration). I'm also going to interpret "succeed by X", as "this test gets +X difficulty". This will turn a review of one weapon into a review of three weapon with direct comparisons to other existing weaponry, in an attempt to gauge the power-level of this card:

First, say you have a heavy aversion to risk, and really just want the cheap +2. This weapon might as well read "Spend 1 ammo: FIGHT, You get +2 for this attack", in this case. There exists one other weapon (as of Dream-Eaters) that provides a +2 boost without additional damage: Gravedigger's Shovel. A quick comparison shows that the imaginary .41 Derringer falls way short: for one less resource and two less exp, you get the same boost an infinite number of attacks, plus a little extra versatility to boot. So clearly you won't be getting this weapon for it's base effect.

Next, let's say you really like the un-upgraded .41 Derringer, and care little for extra bells and whistles. In this case, the text is equivalent to "Spend 1 ammo: FIGHT. You get +1. This attack deals +1 damage". Sound Familiar? It's a .45 Automatic, albeit for for less resource, and one less ammo. Sounds fair, right? Except the .45 Automatic costs no exp, so to be equivalent in power to a card that costs 2 less exp is a bad sign, and thus, this imaginary weapon also falls short.

Finally, the big one. "Spend 1 ammo: FIGHT. You get -1. This attack deals +1 damage. Gain an additional action (limit once per turn)". This would be the only weapon in existence that would reduce your for the attack, if it existed. And yet, if you're gunning for the biggest prize, and as proven in the prior example, you'll be playing with an inferior weapon if you don't, then you have to consider the difficulty value as three higher that it's actual value.

If, say, you want to succeed despite drawing a -3 (the staple standard for tests at medium/hard difficulty), then you want to have a final at 4 HIGHER THAN THE TEST. Not impossible, but damn are you shooting for the moon for this extra effect.

The funny things about rouges is, despite having the second largest select of weapons to guardians, not one of them have a value higher than three (until the Dream Eaters came out, I'm getting to that). Of the rogues that do have 3 , "Skids" O'Toole has access to guardian cards, Jenny Barnes can pull off some magic with Money Talks and Well Connected, and Finn Edwards does like his illicit card synergy. Whether that's enough, I'll leave to you, because personally, I'll not sold on the idea. A better candidate would be Leo Anderson, especially with Beat Cop, who, with all the expensive allies he'll undoubtedly have, might appreciate a cheaper weapon alternative.

...And then along comes Tony Morgan, blowing all other candidates out of the water. Unlike the others, he's a combat thoroughbred, unlikely to be doing anything other than fighting (don't you dare mention seeker Tony). He alone can make .41 Derringer work, in my opinion, and not a moment too soon, as I like the "succeed by X" archetype for rogue, but never really got to see the fighting version of it (alongside Switchblade), until now.

I want to make a point about this card, and it's three cousins "Watch this!", Eureka!, and Resourceful, skill cards with three, fixed, distinct icons.

These are, in essence, win-more cards; cards that get their value when you commit them to tests you're already likely to succeed, and will fail you should you be looking to even the odds against a skill test that's beyond you. They will only ever add +1 to whatever test you perform (save for some fringe cases where two attributes are being tested in one skill check), and they pile on the pressure to pass that test, as the gap in outcomes between success and failure widen from committing this card.

Skill cards lie on a sliding scale between improving your odds of succeeding versus increasing the rewards for doing so. Cards like Cunning and Inquiring Mind occupy the former extreme, Inspiring Presence and its ilk occupy the later, and the core set neutral skill cards (e.g. Perception) define the middle ground. When picking which skill cards to include in your deck, you need to be mindful of which extreme they lean towards.

If you're planning to make use of an investigator's base attribute of three, then forget about win-more skill cards: your success will never be guaranteed without a +2 boost to that attribute MINIMUM. If you have base attribute of 4, the odds will be on your side on the easiest of tests (i.e difficulty 2 and below), but if you have an attribute value of 4, then you're likely expected to take on the harder tests (i.e difficulty 4 and above), for which win-more cards alone won't cut it. If you rock a base attribute of 5, then you're golden; include these cards to your heart's content...

...Which leads to the catch-22 of Inspiring Presence and co.; that they have three skill icons for different attributes, but will only really find use in test with base attributes of 4 or above, of which no investigator has more than two such attributes, and only a handful have more than one. You'll do yourself a dis-service should you spread yourself too thin,.

So here is the big conclusion of this review; the flexibility of this card exists NOT at the game stage, BUT AT THE DECK-BUILDING STAGE. In essence, these win-more cards are almost identical to Vicious Blow, Deduction, Fearless, and Survival Instinct; they just have a place in more decks thanks to the icons. Using the example of Inspiring Presence, most Guardians would compare this directly to Vicious Blow, but other takers, like Jim Culver or Joe Diamond, could very well make the case of replacing (or complimenting) Fearless and Deduction respectively in a more ally focused deck (like for instance, Olive McBride and Dr. Milan Christopher post Taboo List).

These cards are easy includes into decks that can make use of them, their power deriving from benefits that require no actions OR resources to play. Just, take care to not fall into the trap of thinking your deck is now all-purpose; just because the deck-building metrics tell you you've got a lot of , , and icons in your deck, doesn't mean you're going make use of all of them.

Edit: Weirdmarine asked in another review how many cards Harvey Walters could draw. The answer is too big of a comment, so i updated my review.

First assume the following cards are in play

• Dream-Enhancing Serum
• 2x Laboratory Assistant (add Charisma for a second ally slot)
• 2x Arcane Enlightenment (add Sign Magick with Versatile for a third arcane slot)
• 2x Vault of Knowledge.

This brings him to a max handsize of 18 and only the first copy counts against your handsize. With those 7 cards in play your deck will be smaller. So you're likely drawing more cards than your deck and discard have so you'll take horror each time you shuffle your empty deck and go insane.

Even outside Harvey (without Vault of Knowledge) you end up with a max hand size of 14. So you still draw lots of cards that could make you go insane as well.

Updated review of this card

Seekers have a lot of card draw, but redoing your hand is very powerful, especially when your cards don't help or you ran out. on some encounter cards can result in that.

Combos

• Playing this with any version of Ancient Stone in can deal homungus amounts of damage or heal horror (but it provokes an OA).
• Increase your hand size to draw more cards
  • Dream-Enhancing Serum
  • 2x Laboratory Assistant (add Charisma for a second ally slot)
  • 2x Arcane Enlightenment (add Sign Magick with Versatile for a third arcane slot)
  • If you're playing Harvey Walters, 2x Vault of Knowledge

Alternatives

• If you're looking for specific cards, use No Stone Unturned or Mr. "Rook" instead. The first can also be used to help other players
• Cryptic Research costs 1 fewer XP, no ressources and no action; Can also target other players

I really want to like this card in a Carolyn Fern deck for the theme alone - and the fact that she can't play any weapons level 1+ and is so good at getting clues. But I feel a bit bad about putting an enemy back in the deck, and in some campaigns there aren't a lot of humanoids. I'll start with it in the deck but have a feeling it will go pretty quickly once the fighter types in the group get amped up.

This weapon is so well oiled, it won't stay stuck in slimy spheres (good on you Diana!)

However, it still requires you to get close to your target, so it won't protect you from a haunted sarcophagus (sarcophaguses? sarcophagi?)

Also, don't expect it to catch anything flying either.