[Iridios]

Where in the core book does it describe the Armor stat for a spirit?  I've tried searching the book and cannot seem to find it.

[ZeConster]

IIRC, Spirits have the Immunity Against Normal Weapons power, which gives them Hardened Armor against non-magical attacks (that they aren't allergic to) equal to twice their Force.

[Iridios]

I remember that from previous editions, but cannot find that anywhere in the core book nor in the Errata. 

[Iridios]

Found it!  Spirits have the Materialization power which grants the Immunity to Normal Weapons power.

[Equinox]

I remember that from previous editions, but cannot find that anywhere in the core book nor in the Errata.

Got it in one, chummer.  That bit caused no end of grief for our GM (complains bitterly about the rules layout).  Stickies and cheatsheets have been a great help.