In over a hundred attempts at Ifrit I have never seen chatlog weaponskill texts appear AFTER the skill itself.

Noctis is right about the chatlog being 100% foolproof, but that doesn't man you will dodge 100% of the time by simply looking at the chatlog. The chatlog is 100% insofar as displaying the enemies actions before they visually appear - but dodging those attacks depends 100% on the player observing that chatlog.

If you notice the skill 1 second too late you wont have the time to react in time to dodge it. What's easy about Ifrit's hellfire is the fact that the infernal nails appear on the board 55 seconds aprox before ifrit jumps in the center of the ring and readies hellfire. Essentially you are given a 1min heads up that cannot be missed.

As for 100 tonze swipe and swing ii don't think there is a one minute hint so you really have to be on the ball about watching that chat log. Furthermore, if you do indeed need to run towards for one and away for the other, positioning is key.

If all else fails, lower your graphic settings under the desktop FFXIV Configurations launcher.