So I was doing some dueling in Cyrodiil, and noticed that there appears to be a "lock out" for block immediately after weapon swapping. Your character still does the block animation, but hits go through unmitigated (this was especially noticeable against Wrecking Blow because of its knockback effect). This happens if you are holding block and weapon swapping, or if you start blocking right after the swap. Either way, there is about a 2 second window (hard to calculate exactly) beginning once you swap where your block doesn't work even though your character is performing the block animation. If I had to hazard a guess, it seems like the weapon swap cooldown is also not allowing blocking during that short timeframe. There was no server lag happening, and when I asked people about it in-game they said they had also noticed it, so I wanted to post it here to see what other people have observed.