ToME: the Tales of Maj'Eyal

What type of critical chance is used by weapon-based talent that is also spell/steamtech/mind power (such as "draining assault", "spinal break" etc)?

More specifically, what type of crit do "mutated hand" and tentacle-based talents use?

They are usually phys crits.

Tentacle attacks use a specific tentacle weapon, and so use phys crit.