An effort to translate the Japanese Wiki page and to educate on what the various effects do. I'll be throwing in my own observations and estimations if applicable. Feel free to correct me, as the guide was made ham-handedly :p

Overall Advice: You must dodge any of these effects if at all possible. Blocking still allows for the status effect to proc on you. If it hits you, you can be affected.

NOTE: It is unknown to me if status can stack. If that is possible then multi-element enemies/groups present pose a much higher threat.

Burn
The most common effect where damage is distributed over a long period of time. You'll know when you're affected due to the fire sound effects and you character looking like the Human(Oni) Torch. This is the weakest of the damage status effects characterized by the following:
-Small damage
-Deals damage over a long period of time
-Damages in 1 second intervals
You can deal with this by manning up and taking the damage. It doesn't do enough damage to put you danger unless you are already low on health.

Poison
One of the earliest case of WTF deaths until you figure out how deadly this status effect is. The visual effect is a green bubbly haze around the character It functions like Burn save for the following:
-Lasts longer or just as long as Burn
-Deals 2x or more damage than Burn
-Damage is dealt 10x faster than Burn
Without sufficient prevention or a method of curing the status effect, you will quickly die from this status effect, even from full health as the damage prevents natural healing and it will continue to damage you through any animations.

Paralysis
This status effect is very similar to the Shock effect in Spiral Knights. The visual effect is you glowing yellow with lightning bolts occasionally shooting from you. It is characterized by the following:
-Prevents the use of your weapon skills
This seriously hampers your damage output but at least you're allowed to move at full speed and use items as well as able to switch weapons.

NOTE: From here on out, I haven't experienced these status effects so it's straight off the wiki with guesses as to how deadly they'd be.

Freeze
This status effect is very similar to the Freeze effect from various games. Your character will be encased in an ice crystal. It is characterized by the following:
-You cannot attack, move, use items or skills
-Breaks upon taking damage
If I know anything from Dynasty Warriors Multi-Raid 2, it is entirely possible for enemies to reapply Freeze on you, effectively chain-stunning you and teabagging you to death, especially if the Freeze proc is on a multi-hit attack.

Slow
This status effect can only be dealt from specific weapons wielded by you or if you drink certain alcohols to have it applied to you. It's similar to Slow effects in various games. Enemies are a distinct purple when under the effect. It is characterized by the following:
-Movement Speed Penalty (-50 Movement Penalty)

Stop
Only enemies currently proc this status, there are no weapon skills with Stop. It works like Stop in various games. It is characterized by a ticking clock on your character. It is characterized by the following:
-You cannot take any actions like Freeze
-Damage does not end the effect unlike Freeze
This effect is deadly, as the enemy has a free shot at getting massive multi-hit attacks on you.

Stun
This can also be called "hit-stun" as the Japanese wiki characterizes this as when enemies faceplant into the floor or when you reel back from critical hits or other abilities. Abilities like Charge Strike proc Stun.

Rest
This effect is applied when you sit, on jewels and certain liquors. It is characterized by the following:
-Increased Natural Health and SP Regenertaion.

As for freeze, it occurs when you get hit by an Ungaikyou's flying ice attack. Should you get frozen, you well remain stuck in the frame of animation that you were hit in, even if you were in the middle of dodging. Of course, you can't anything at all for about 5 seconds or so while an enemy like the Ungaikyou blasts you into pieces with its lightning.
So it itself is not deadly due to damage but is deadly due to leaving you a sitting duck to other attacks.

Annnd Most Importantly. Don't forget too Up-Chuc! .......

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Always, Up-Chuc(Use Plenty of Caution Handling Unstable Crystals)

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Oh wait.. Thought the thread was named "Crystals and You" Whoops XD

Ha!! I knew all that hours spent on Pokemon would finally pay off!! They denied it... they refused to believe it but the truth stands!!

"Blocking still causes status effects"

Well that's really retarted. And block only lowers damage... why include the mechanic if it has so many drawbacks?

Its not as bad as you think.

The damage from status effects is negligible later on.

What you have to worry about instead, is more severe ones such as stillness and freeze >_<

Sparhawk wrote:"Blocking still causes status effects"

Well that's really retarted. And block only lowers damage... why include the mechanic if it has so many drawbacks?

It blocks a lot of damage. Odin normally caused me about 1200 damage on hit, but in guard it's more like 50 damage.