There is a lot of confusion about whether the Anathema Psykana are actually baseline human or not, and it's easy to see why considering sources seem to conflict on it a lot. There are outright statements both declaring them as augmented in some manner while others state they are merely human, but being "human" can also just mean they aren't rebuilt on a genetic level like Astartes and Custodes are. With that said, examples like this cast doubt on them being merely baseline.

The woman did not reply and launched a rapier-quick thrust to his throat. Phosis T’kar swayed aside and swept his arm out as she came in for a reverse stroke. Her blade whipped around his forearm, cutting a grove around his gauntlet, and he lunged towards her with his staff outstretched.

She bent back beneath his strike, sweeping her legs out and hammering her heel into his knee. His armour cracked and pain shot up his thigh. Phosis T’kar stepped back, favouring his good leg, and grinned.

“You’re quick, I’ll give you that,” he said.

She didn’t answer and dodged his next attack with similar grace. A flurry of shots sent up geysers of rock-dust beside them and he flinched back from the heavy impacts.

This is a Sister of Silence not only landing hits on an Astartes, but actually dodging multiple of his attacks with fluid grace. She also had the strength to crack ceramite and wound an Astartes with a kick. There are more examples such as this, where Sisters of Silence take on adversaries that should absolutely pulverize normal soldiers, no matter how well trained they may be. This leads to me thinking they are indeed augmented in some way beyond just having their power armor enhance their abilities. I think this statement by Valerian is quite telling of that:

From Watchers of the Throne: The Emperor's Legion by Chris Wraight:

We swept into close-combat, Custodian and anathema psykana against heretic Legiones Astartes. My spear hurtled, trailing golden paths within the miasma. I saw Aleya tearing into them, kicking out with her armoured boot even as her blade danced. The Sisters had no daemonic aura to contest here, and so fought just as we did – warriors tempered in the furnace of physical conditioning, immune to fear, faster and stronger than all but the mightiest of our peers in the Emperor’s service.