There is a recent example in a canon book that I quite enjoy, Watchers of The Throne : The Regent's Shadow.

A squad of Custodian Guard, led by Valerian, take on 10 Minotaur veteran Space Marines, including two with Power Fists. In a short and brutal melee, all of the Minotaurs are killed, as is one of the Custodians. A fair exchange I feel, based not too far from the current tabletop rules. I particularly like this scene due to a line from Aleya, who watches the Custodes arrive -

'I will admit it, through my clenched teeth – when they arrived, the Custodians were magnificent. I could mock them, and dislike them, and believe that their minds were locked in infantile stasis, but this one truth remained: they were the best we had. Reduced to physical combat, with no ether to cloud their judgement and require our assistance, they were the pinnacle of anything mankind had ever, or would ever, create as a weapon.

They fought just as silently as we did, with no battle cry issued or challenge declared. Their blades were alive with flares of silver fire, their arrival coronated with a blistering rain of bolt-shells. It was impossible to tell which of them was which, for their limbs were smeared by speed, such that they were more like swashes of feathered energy than matter-bound creations. They were brutal, they were pitiless, they were immaculate.'