TL:DR: Extremely self sufficient weapon, great for 3 characters who want to focus on or if they just want a backup alternative to Shrivelling.

characters typically run weapons, don't, ergo the disparity in buzz for the two variants of this upgrade.

I would like to argue that Enchanted Blade is no slouch, even compared to it's very impressive cousin. Three characters in-class, Diana Stanley, Jim Culver and Akachi Onyele have 3, with blade in hand they fight at 5, by spending charges they fight at 6 or 7, this is by using the mechanics of the blade all by itself, no support required! With some very light support, a couple skills like Overpower and/or Vicious Blow you can fill a support fighter role killing off a few 2-4 hp threats. It's terrific solo where the self sufficiency is key.

The charge mechanic is very efficient, you basically have a +5 base attack and 4 vicious blows on retainer. You can kill 2 3hp threats in 2 attacks, or 2 4hp threats in 4 attacks. The relatively few charges reinforces the support combat role, you can defend yourself in solo or multiplayer or perhaps spend the entire weapon to beat a boss, but it's a one and done deal with probably no backups. I kid! You still have a copy of Shrivelling right!? Not to mention the infinite number of buffed 1-damage attacks.

Point of reference, a fully charged Enchanted Blade attack is 1 from being exactly as powerful as a Lightning Gun shot, you get 2 shots at the cost 3 resources!

There is a big, obvious downside. characters love their Arcane slots. Jim and Diana don't mind too much, their isn't that impressive anyway, but Akachi likes to play the Rosary game so I doubt sacrificing card slots and XP for a card interests her much.

P.S, the sheer power of a fully charged Enchanted Blade can even make fighting work for a 2 character, obviously it'll require a little bit of card support, Agnes Baker with her cards or a certain brand of Norman Withers can actually be very hard-viable with a sword-fighting build.

Normally I think of Enchanted Blade as a weapon designed for guardians, since the additional cost of an arcane slot means nothing to them but is very painful for mystics. But since this version of the weapon can only be taken by mystics, I thought it was an interesting exercise to compare it to a spell instead, Shriveling (3) in particular, which has the same resource and XP cost, and compared to spending one charge on the blade, is the same number of uses for the same damage.

To make this comparison directly you have to pin down the relative willpower and combat ability of the mystic. I feel that a mystic whose combat is only two points below their willpower (for instance, Jim Culver with St. Hubert’s Key, or Akachi without a willpower bonus) is a relatively muscular Mystic who would be a good candidate to wield a blade, so I made the following comparisons assuming combat equals willpower minus 2:

Advantages of Enchanted Blade:

1. Allows you to spend two charges on a single attack for double the bonus. This is a huge advantage since it is actually very efficient to do so when fighting an enemy where the extra damage is useful.
2. Enchanted Blade can be used without spending charges, and is equal in combat ability to the Sword Cane for this purpose, without having to spend the extra card and resources to play the Sword Cane, and without the limitation of having to exhaust it.
3. Enchanted Blade does not have the risk of causing horror damage.

Advantages of Shriveling:

1. Compared to using the Enchanted Blade and only spending a single charge, Shriveling gives you +1 fight ability.
2. A Mystic is likely to have lots more ways to commit cards with willpower bonuses or otherwise boost willpower, fewer ways to commit cards with combat bonuses or otherwise do anything to boost the fight ability on Enchanted Blade.
3. This card can be upgraded to Shriveling (5), which is a very impressive upgrade and is much better than the blade if you frequently fight foes with 3 health or with 5+ health.
4. Some decks may find it helpful that this is a spell rather than an item (such as a deck using Arcane Initiate).
5. Does not require a hand slot. If you use your hand to hold a Sword Cane, you can use it to evade, which Enchanted Blade cannot do. Or you have the option of holding something else in that hand.
6. In order to keep using the Enchanted Blade’s ability to fight without charges, you have to keep it in play eating up a spell slot. If you play Shriveling and Sword Cane instead, you can replace the Shriveling with a new spell once you run out of charges, and the Sword Cane will stay in play.

After doing the comparison, I felt the Enchanted Blade is more impressive than I first thought. I don't think either the blade or the spell clearly wins the comparison, it depends on the character, but the blade looks like a perfectly reasonable choice for the deck of a Mystic with good combat ability, despite costing a spell slot.