Natural 20/1 Crit fails and Crit successes, How do you handle them?

[CleverNickName]

I run a cinematic pirate-themed campaign setting, where the players do all kinds of zany stunts like swinging from chandeliers, leaping from balconies onto moving wagons, and so forth. Rather than create a dozen house-rules for these stunts, I use the Crit mechanic to tell us when a cinematic event triggers, and I let the player decide what it looks like. The way it works:

On a crit, you can choose to have your attack do extra damage, per the rules. Or you can choose to do regular damage and:

• trade places with the target or an ally
• knock your target prone
• kick dust in your target's eyes, blinding them until the end of their next turn
• knock something out of your target's hand
• disengage immediately
• knock the opponent back 10 feet
• anything else you've seen in the movies: ride a shield down a stairway, jump on the dragon's back, swing on a rope across the deck of a ship, etc.

Most of the time, my players choose to just deal extra damage per the rules. But every now and then, it's more important to knock that ceremonial goblet out of the cultist's hand, or escape an ambush, cut the One Ring off of Sauron's finger, or knock the bugbear down so that the rogue can finish it off. It doesn't happen a lot, but it's always cinematic when it does.

 

[TheSword]

So my next D&D campaign is going to add in an element of degrees of success.

Where on non-combat rolls a over achieving by 5 gets some kind of boost and by 10 gets something substantial.
Failing by 5 or more gets some form of disadvantage meanwhile failing by 10 gets results in a more tangible disadvantage.

For instance succeeding an Arcana check to work out the features of an aboleth might reveal a strength and weakness. While +5 might reveal all of them. A +10 might reveal them all and give you advantage on your next save against them.

However failing by 5 might reveal some incorrect information. While failing by 10 might give you disadvantage on the next save the creature forces on you as you badly miscalculate what the creature can do.

This isn't particularly original. There has long been a history of falling if you fail a climb check by more than 5, or sinking if you fail a swim check by 5. This is just continuing the approach.