Dissection tools are an interesting mirror to Hawk-Eye Folding Camera, and are another example in a long line of cards which go to show how clues and kills are really not symmetrical at all, which holds back dissection tools in terms of value compared to its camera counterpart quite a lot, but which still can find some nice homes.
Firstly, lets get this out of the way, the problem with this card is not that its a card that asks you to kill things that is yellow. That is fine, plenty of seeker or seeker accessing characters kill plenty these days.
The two core issues with dissection tools are the relative value of hand slots for different roles, and timing issues.
Giving up a hand slot for a small investigation boost is a fairly standard thing to do. While handslot investigation items can get even more beefy than an effective +1, because you spam investigation tests so often, a mere +1 is fine. And because most handslot investigation tools can't get more than 1 clue without drawbacks or build around strategies, and clue gathering doesn't have critical windows you need to hit every turn to avoid taking a burst of damage due to the fact that the 'damage window' for failing to gather clues fast enough is the total length of the scenario in doom, its ok to just consistently grind away at them, using a small passive boost to be the equivalent of a fractional clue gathering rate increase is fine: Going from getting .7 clues an action to .85 is still something like an entire extra turn for the cluever per-player per-scenario.
For combat however, your combat assets tend to be providing a lot more than just a +1 to hit, both in the sense the value tends to be greater, and because damage acceleration is very important. If your hitting 85% of the time vs a 3 health enemy, statistically you will fail to kill them within 1 turn on almost half your combats, forget about killing more than one enemy, which is why weapons are so important. So you need to dual wield this with a weapon, which raises the question of why you aren't just using a two handed weapon. The value of one handed weapons is, traditionally, you can take a secondary utility item with them to find clues or help your team, in exchange for their performance being noticeably worse than two handed weapons. For the vast majority of gameplay scenarios, a +1 to hit, evade, and +1 to sanity is just not worth the loss in output.
The second issue of timing is also big: even if you theoretically could slot this alongside your weapon, say... if your Joe Diamond, clearing a location of clues is a lot less timing specific than killing at least 2 enemies. Clearing a location of clues happens any time you earn a victory point, it is your primary objective in any Arkham scenario besides actually clearing the scenario, and if you find your camera half way through a scenario, you still probably have quite a few investigations to go where the +1 investigation will be a difference maker. For combat, half way through the game may mean you have plenty of fighting left in a big 4 player game at a combat heavy scenario, but it could just as easily mean you are only going to see 3-4 more enemies in the game if your playing duo or at a more mellow scenario. You don't just constantly fight like the way you constantly investigate, and in that lower end you are only seeing that +1 for 4, maybe 5 attacks.
There are characters who can make use of this though. Finn, for example, enjoys even the first level of the effect, often will go out of his way to use a 1 handed weapon as his primary combat tool over 2 handers even as a dedicated combatant, draws extremely fast, and can use other methods of gaining team utility than hand slots. Roland and Joe have Bandolier and often will take enough items to be running Backpack as well.
But it definitely isn't a power option, at least right now. If there comes a point where a handslot bonus to fight (of which this and Boxing Gloves are the only options in the entire game) becomes more valuable, and the ability to force kills becomes easier, then this might become stronger just because its functionality is so unique, but unique doesn't mean good or special. Often times things are unique because no one really wants it outside novelty, and a static combat bonus in the hand slot just isn't that useful in the current state of the game.