Mano A Mano achievement in Onimusha: Warlords

From the Onimusha online manual:

"When facing off against certain enemies, sometimes they'll initiate a power struggle. If you win the struggle, the enemy will lose their guard, giving you a chance to attack.

To win power struggles, you'll have to use or ( ) and press buttons more than a set number of times."

Translation: When you lock swords with a demon, move the left and right furiously while simultaneously spamming in any order.

Enemies that can initiate a power struggle:

Red Skeletal Samurai Demon
Hulking yellow Demon with an Ax.

Here's a video if it helps:

TheOnlyMatto suggests another approach:

"I found this strategy worked best:

Hit the Axe wielding demon immediately after dodging one of his attacks. He should go into a defensive position which is how you initiate the mano a mano power struggle.

I mashed only and plus wiggled the .

I found that the axe guy was slower, easier to dodge and way easier to get into a defensive position. It doesn't initiate by hitting each others weapons, it is when he holds his weapon across his body to block you that it initiates. Hope this helps someone else."