You will generally start noticing patterns as you get to fight an opponent longer. What I usually do is block the first few times they feint spam, during which time I try to see what their pattern of attack is. Most people I've fought engaged in swing - blocking for a couple of exchanges then employed feint spamming. It's a bit of a gamble, but usually people start feint spamming after they notice their first few simple attacks are not getting through to you. If you can determine the pattern and see after how many exchanges, in general, they start feint spamming, you will know when to spam them (double hit), or at least "feel" when they're about to break the flow of swing - block. You can also take the gamble of starting an attack as soon as they start feinting, but it's less reliable than reading the enemy.