Wyrd
Wyrd is a representation of a Character's path, their destiny, it is a measure of how much control an individual has over their fate.
A Character with high Wyrd seems to take horrific [Injury] after horrific [Injury] and yet receive nothing more than a scratch, looking one second as if they had lost an arm and with a blink the lost arm is just a nick on their shoulder.
Mechanically Wyrd is how a Character can avoid [injuries] and other bad outcomes through the "Not Today!" Free Action.
Wyrd and consequently Wyrd Points are a special resource in that they do not regenerate in anyway other than increasing Wyrd itself, once you are out of Wyrd Points, they're gone forever!
Wuntch's Whatever
Wyrd is MEANT to be spent, while yes this is an RPG and your character is yours to play, i would strongly recommend not hoarding their Wyrd like consumables in every elder scrolls play through ever 
. Part of the fun and thrill I find in Meat Space, is the threat that your Character may meet their untimely end or perhaps lose a limb during any encounter, and that's ok. Go forth and spend that Wyrd when you need to, get to that last session and have one single point left that comes in at a critical moment when death is on the line and BAM! Chargog the Zerk miraculously survives the disintegration beam that would've turned him to so much dust! All this to say there can be a lot of fun in spending your resources, it can lead to game mechanics driving narrative tension and player excitement.