The world building in Arkham is always very good, but you need to use some imagination to understand why some cards say what they do. In this case, jumping from the balcony directly to the ground floor would definitely hurt, so you need to take 2 damage. It's those little things behind the card text that make them so great.

An important question that came up while playing. If Roland takes 5 mental trauma while playing this directive, does he go insane? Or does this functionally give him health and San of 9/8? If he breaks this directive with 5+ horror on him, is he immediately defeated due to horror?

This was a pretty useful addition to my Dark Horse Patrice deck. It let her stash resources "off the books" and use them to pay for the relatively limited number of items in the deck that she absolutely had to be able to play when they came up (Moonstone and Patrice's Violin are very timing dependent), plus the odd extra. It's more or less an Emergency Cache where the action to play is divorced from the time you use the resources. I suspect the "stashing" effect is a benefit in most Dark Horse decks, but I've only played the one.

I also love that it uses secrets; I am sure Schoffner's motto is "The Secrets are the Savings!"

"I've got a plan!" is the obvious comparison and unlike what I first thought when looking at it, I think it actually compares fairly well.

I've got a Plan has a slightly higher cost and does not give any bonus intellect. In many cases, you'd probably want to commit a card or two to your I've Got a Plan anyways to ensure you land the hit (missing a 3 cost event really hurts your tempo), so the cost of discarding cards for occult invocation isn't actually as bad it first seems.

This card actually gives you some flexibility to deal 1-3 damage, and choose how much you want to commit. The tradeoff is slightly lower max power (3 vs 4 damage, and commiting 2 cards to I've got a plan might give you up to +4 skill instead of 2 on occult invocation).

The other downside of I've got a Plan is you need a bunch of clues to even use it. Of course, holding even 3 clues isn't hard for a seeker, it's their primary role after all but sometimes the timing is just not right (e.g. right after advancing agenda), or you're playing solo and there are less clues in play, and specific scenarios don't have a lot of clues. Cards in your hand in contrast are always available and relevant for every scenario. In fact, drawing cards are seekers specialty.

I think you'll take this over I've got a Plan if...
-you're playing solo
-your deck has a decent draw engine
-you need to run a lower cost curve

You might lean more towards I've got a Plan if...
-you have high intellect / plan to stack intellect stats and don't need any other boosts
-your fighter might need a bit more help dealing damage vs bosses
-the cards in your deck are valuable in setting up a combo of sorts
-you can grab clues instantly at any time (e.g. working a hunch)

Looks really bad to me. Two actions, 2 resources AND a non-boosted test on a specific enemy type to lock down a unit. Locking down a unit is essentially killing it, but probably a bit better since it doesn't go into the discard pile to recycle and come back. It has also has a bunch of niche uses like Trish Scarborough or Tommy Malloy that others have mentioned. On the flip side based on the FAQ, there are few, rare situations where the enemy can still hurt you while in play.

Surprisingly in faction I think this card is most similar to Monster Slayer. Both require a Strength test, and some resources to insta-kill an enemy. Handcuff requires an additional resource and action but costs 5 exp less. Unfortunately Monster Slayer (5) is pretty bad and I'm guessing probably never used. I'm thinking it might see more play around 2 exp.

I say this because Fang of Tyr'thrha exists at 4 exp. That essentially kills the enemy at any revealed AND lets you teleport, AND gives you stat boost. Out of faction, survivors have Dumb Luck which also removes an enemy from the board after a skill test with a generous margin and that only costs 2 exp.

If you look at Heroic Rescue vs. Heroic Rescue, for 2 exp you pay 1 less resource and can use it in adjacent locations (which I'll indirectly proxy as 1 action to move). Going from handcuff to a hypothetical 2 exp Monster Slayer, it has the same upgrade value, you would pay 1 less resource and use 1 less action.

Personally I'm not a fan of Handcuffs though, 2 actions to 2 resources to kill something seems way too slow and inefficient. I compare it to Spectral Razor which only takes 1 action, has an easier test, gives you a free engage and will kill most things already. Guardians likely have better ways to deal with enemies and only targeting humanoids (and non-elites) really makes it hard to slot into your deck if youre going in blind.