How is a Servo-Arm used as a weapon?

Question

My player has a Techmarine with a Servo-Arm, but I can't find statistics for it or what kind of action it takes to use in combat.

In the talent description of Mechadendrite Use on page 123 it states:

Servo-Arm: Servo-arms are powerful mechanical arms fitted with piston-driven claws that are equally effective as weapons as they are at repairing machines.

I haven't been able to find weapon stats for a servo-arm in the rule book though. Where are they listed?

Also, if my player's Techmarine does want to use the servo-arm as a weapon, is that a standard attack or can he use it additionally to his standard attack? What kind of action would it be? A half action or maybe even a free action, as the character only has to spare a thought to move the arm?

Answer 1

I have found the entry in the rule book myself.

Page 177 of the Core Rule book:

Astartes Servo Arm [...]The Techmarine may strike with the arm as his Reaction for the round or as a Standard Attack during his turn (so long as the servo-arm only makes one attack per round). This attack uses the Techmarine's Weapon Skill, and deals 2d10+14 Impact Damage with Pen 10. Exceptional craftmanship servo-arms increase their Strength value to 85 (increasing damage to 2d10+16) and add a +10 to Grapple Tests.