The official GemStone IV encyclopedia.
The Arachne acolyte's head is clean shaven and bald. Where hair once grew, ornate tattoos of deep red hue decorate every visible bare body part. The Arachne acolytes are muscular but lean. Long years of study and training has produced fanatical allegiance to Arachne. Any semblance of humanity has long since been exorcised through torture and meditation. Only the zealous duty of Arachne now compels their existence.
Arachne acolytes can disarm you of your weapon, which it may pick up and use against you in its next turn if you do not reach for it in time. Since disarm occasionally inflicts roundtime, players can potentially lose their weapons in this manner if they do not have a suitable spare.
Arachne acolytes appear to enter multiple states of "shock", perhaps after attempting to cast a spell after running out of mana. This will stun the acolyte, inflict minor damage, and cause nerve damage. An example of this effect is shown below:
An Arachne acolyte appears to have sustained massive amounts of system shock!
... 20 points of damage!
Heavy shock gives the Arachne acolyte fits!
It is knocked to the ground!
The Arachne acolyte is stunned!
Also the acolytes usually wear chain hauberk armor, so including their TD they will also have a -6 CvA from their armor making it harder to ward them with spells.