Weird to see that this is a card with only one kinda old review, especially since I often hear it talked about as almost the gold standard of weapons, often thrown into any fighter or flexer who can take it - which is pretty much everyone to begin with.
That said, I have a controversial opinion about this card; it's the worst exp weapon in the game. If Song of the Dead and Fire Extinguisher (1) didn't exist, I'd probably extend that to calling it the worst exp fight asset in the game. I would only really consider it in characters who generally have no other option, or characters who would really prefer not to run in-class weapons, who it certainly has a place in.
Now, I don't think this was always the case. A lot of excellent weapons have come out recently, particularly in Edge of the Earth. Before cards like Meat Cleaver, Fire Extinguisher (3), Chainsaw and Sledgehammer existed, it must have been a pretty strong pick in Survivor. Even compared to Guardian big guns, it at least had the benefit of infinite uses, but now there's Sledgehammer, Butterfly Swords, Holy Spear and, of course, Cyclopean Hammer to outshine it in that niche. And while all of those take up two hand slots - well, now guardians have a nice sidearm that doesn't take up a single hand slot and can be used efficiently against lower health enemies.
The appeal of the card, too, is obvious. A single weapon that you can slam down turn one and be consistently fighting with +2 for 2 damage definitely sounds like a good deal. And its once per game attack seems decent enough as a boss killer. That said, the second attack is extremely limited. It can only be even attempted once, and while its damage is high, if it kills a boss, there's a lot of levels where the draw is not likely to be very useful after that. And of course, using it as an opening attack loses you potential of the draw. But even so, just the first effect is a very strong one, especially for a card that, taking up a single hand slot, can be run alongside almost any tool you could care to name.
So, with all of that, why do I think it's the worst exp weapon in the game? It's a simple factor; cost. 5 cost, 5xp for a weapon that is simply efficient and infinite, is completely prohibitive. 5 resources can block off any number of other important cards to set up, and when drawn late can be difficult to get out. Costing the entire pool of starting resources is perhaps fair for a weapon that could last you the entire game, but with one major exception, all of its in-class competition is cheaper (or the same cost but better), and much of that can also last the whole game, while also being played out with an ally. 5 cost is also a very significant number for an Ever Vigilant starting turn, with the cost of 5 prohibiting it being paired with anything but a single 2-cost or multiple 1 or 0 cost cards. This rules out every significant guardian ally. In most other classes, it likely rules out playing even a single other asset - which can be very bad news if something like Crypt Chill is in the encounter deck. Some economy cards can help with that, but that starts to become very dependant on a specific opening hand of brand, economy, and a card cheap enough to be played by the econ card. No option for drawing, either.
The second factor of the cost is its experience cost. Two copies of this will set you back 10 whole exp. That's an entire extra weakness in standalone mode, and is something very unlikely to be earned in a single level. But if the card is good enough, it generally doesn't matter how fast you can buy it, or whether two copies are spread across two levels. And, of course, if your draw or search is enough, you could potentially get away with only a single copy. It'll be much less likely to be found in your opening hand, but that could well be worth it. It's not like you'd ever need to play the second copy, unfortunate discards aside. But even compared to a single copy, there's a lot of better cards you can buy. Two Beat Cops are cheaper to get out, and will tack on extra and damage to your weaker, level 0 weapons, bringing them almost to par with the brand, at least for a while. Survivors could get a pair of Brute Forces and a True Survivor to recur them. Rogues can grab a pair of infinitely cheaper Switchblades if not using taboo, or one and a Haste to get more tries at hitting with it if you are. Even Seekers have a cheaper, higher damage, higher combat bonus fight option, though it runs out a lot quicker. And any class using guns can take any number of cards to let them last longer for much cheaper than the brand.
Finally, my last point against it is its simplicity and blandness. As a weapon, it just isn't interesting enough for it to effectively synergise with any fun class cards. Rogues can put together a group of guns and Sleight them, or Reload them. You can use Knight of Swords and lean into all the weapons that want to succeed by a lot, and it adds far more to any of them than it would the brand, and to a number of other cards, too. Guardians can also reload or do tricks with their guns, or find much more interesting targets to Enchant. Survivors can throw away their much less reliable weapons for cash and damage, or just keep bringing them back. And all of this doesn't even touch on cross-class options.
Now, an important distinction here is I don't think it's bad that the card is bad. I think this is exactly what a big neutral weapon should be - well, this or the Ornate Bow, its opposite as a unique niche weapon that does something very few other cards can even imitate - a less cost-efficient option than any in-class option you could care to name, but one you can grab if you care more about having a simple, good weapon for the entire game than any kind cost-efficiency. Certainly, plenty of people will value that a lot higher than I do.