An easy way I found to defeat the dual wielding swordsmen is to just shield bash them repeatedly by tapping
until you get the chance to execute them. They only block this sometimes and if you manage to get them up against a wall it is even more effective. If you are fighting two of them just focus on one of them and shield bash, and just counter the other when they go to attack (
), then return to shield bashing.
The way I defeated Boudica was almost the same. Shield bash her once, then heavy shield bash her (hold
) 4 times. She will deflect the last bash, roll away when she does (
) then immediately shield bash her again, even if she is attacking this should stagger her so you don't get hurt. Then heavy shield bash 4 more times, roll back, repeat.