pf2e.fyi
From Pathfinder Impossible Magic, which isn't enabled.

Phase Spike

ITEM 10
Price 900 gp
Usage held in 1 hand
Bulk 1
Category simple
Group spear
Damage 1d6 piercing

The head of this +1 striking astral spear is partially translucent. Thieves and battlefield spellcasters favor it for its ability to pierce magical barriers and temporarily disable enchanted objects. A creature that has Raised its Shield (or similar ability) takes a –1 circumstance penalty to its AC against attacks from a phase spike.

Activate—Incorporeal Stride (concentrate)
Frequency once per day

Effect You focus on the head of the spear and channel its properties into your form. You Stride up to your Speed. You can move easily through solid objects and creatures during this movement, but you can't end this movement within a solid object or in a creature's space. You also gain resistance 10 to all damage during this Stride (except force or spirit damage and damage caused by a ghost touch rune); double this resistance against non-magical damage.
Pathfinder Impossible MagicORC