Supercharge blessing applies 10% brittleness on energized hits. This is fine for the regular power sword, which can spam energized hits on demand, but the Mechanicus power sword requires charges for its energized attacks and only stores up to 6 charges. It would take two-thirds of your power charges to apply 40% brittleness to one target, which is just too weak in the current state of balance. For comparison, System Shock talent applies 10% brittleness on every hit with Arc maul/rifle, and adding Electro-Strike Conduit talent applies it on crit with any melee weapon.
My recommendation is to double the effect of Supercharge blessing only on the Mechanicus power sword, so you can max brittleness by expending 2 power charges. This is still less spammable than other brittleness blessings like Uncanny Strike or Thunderous for other weapons, so I think this is a reasonable buff.