Things You Meet On the Road

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    A group of nomadic ascetics.
They wear bell shaped straw hats that obscure their faces and tattered yellow robes.
They smell truly awful. At first they seem friendly, but are nothing more than carrion eaters. The shovels they carry
serve as an effective weapon, as well as a tool for digging up fresh graves. They commonly travel roads of war.
No longer human.
Slit your throat while you sleep.
    C: 8    HP: 2d6+1    M: 4

They might carry heretical texts, stolen icons, or valuable beads. Never money though.

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    An articulate suit of armour with a trapped soul.
The metal is rusted, the body decayed. Filled with a heavy white smoke
that moves like a liquid. A good conversation can draw out its sense of self.
Smells like burning.
    C: 15    HP: 2d6        M: 9

It could be:
1. Covered in metallic spines which can impale.
2. A slab of steel. Thick plating. Hard to pierce.
3. A chainmail phantom. Flexible, hard to bludgeon.

The inside of the armor can be scraped for crystallized soul essence. d%100x10 dubloons if you can find the right buyer.

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    A Demon of the Typhoon.
It brings the rain. It brings flood. It drowns your fields, drowns your livestock, drowns your family.
Attract the needle of compasses.
They can stand over nine meters tall. Very slender. Appear to be made of water.
A long neck that reaches over the tree tops. Feeds off drowning.
Able to teleport in the rain. Takes damage when its body is polluted(Rust, Salt, blood, etc. but not soil.)
    C: 12    HP: 1d4+1    M: 5    Resists non weakness attacks.

Long slender arms are a cutting weapon (1d6dmg).
With focus, can make a person drown on dry land(upon failed saving throw or constitution check).
    Roll under constitution to cough the water out of your lungs.
Teleportation. Null after taking damage once.

Leaves behind a fist sized core of ice. Never melts.

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Always roll on the reaction table. (C=combat ability, roll under. M=morale)

A different way to use B/X

I have a smooth brain and don't like difficulty checks. Instead I ask players to roll under their stat with a D20.
Add on advantage/disatvantage and occasional +1 -1 and it works pretty well. Armor level reduces damage by that amount (leather -1,plate -3 etc.) 

Also for most basic tasks I just ask players to roll 1d6 and only fail on a 1. Stuff like picking locks as a thief or climbing up a steep surface. Basic tasks with consequence for failure beyond nothing happening.

I don't think you  need to weigh the dice system much. Catastrophe is more fun when its spontaneous, and not actually basically decided by the GM.