Sabin's blitzes are some of the best moves in the game. If you know how you want to use Sabin, and know when to use his blitzes, Sabin can be a very valuable member in your party. I broke each of his blitzes down in this section focusing on how they should be used, and when I'd use each. I listed both the SNES and the GBA names for the blitzes, but I grew up playing the SNES version of the game, so those are the names I use when I mention the blitzes.
Each blitz is learned by leveling Sabin up, but his ultimate blitz, Bum Rush, can be learned by visiting Duncan's house in the World of Ruin. I highly recommend getting it this way, and not waiting on Level 70. Duncan is important to Sabin's story, so it's a neat little scene to watch, and because of its attack power, the move is worth going out of your way to get.
Blitz: Pummel/Raging Fist
Learned: Level 1
What It Does: Throws a bunch of punches on one enemy.
Opinion: A pretty solid starting blitz, Pummel is a great physical attack that will get you through a good chunk of the game early on. It's a great damage dealer, and because it doesn't miss, it should always be used over a normal attack.
Blitz: AuraBolt/Aura Cannon
Learned: Level 6
Type: Magical, Pearl/Holy
What It Does: Casts Pearl/Holy elemental damage to one enemy.
Opinion: In my opinion, this is where Sabin begins to become an asset. Not only is his physical attack, Pummel, great on most enemies, but AuraBolt is one of the blitzes that allows him to deal magical blows without consuming MP. It's also learned pretty early on. This blitz, of course, is more effective if you use it against enemies that are weak against the magical element. I wouldn't use it in place of Pummel as a physical attack, as its strength/vigor are significantly lower. In the beginning of the game you probably won't notice a difference, but it definitely matters later on.
Blitz: Suplex/Meteor Strike
Learned: Level 10
What It Does: Sabin will pick up a single enemy, jump, and slam the enemy to the ground.
Opinion: This is a great blitz if you're facing one enemy, as it will deal double damage. If you've taken down every other enemy in a fight, use this on the last one to end the battle quickly. I would not use this as my main physical attack, though. While Pummel's strength is a great deal lower, it will hit every time while many enemies and most bosses are immune to Suplex.
Blitz: Fire Dance/Rising Phoenix
Learned: Level 15
Type: Magical, Fire
What It Does: Several flaming Sabins will fly around the screen and burn all enemies.
Opinion: More magic without using MP! Additionally, this is the first blitz you learn that targets multiple enemies at once. It doesn't deal much damage to any one foe, but it is elemental, so it's great against enemies that are weak against it. I personally use this blitz to weaken the enemies so that my other characters can take them out faster. If you don't have other great physical attackers in your party, battles can take some time and your characters will lose HP being attacked while you wait on Sabin's turn to roll around again and again. Use this to weaken the enemies, and your other characters with lower attack stats will have a better shot at taking them out.
Learned: Level 23
Type: Magical, Healing
Strength: Depends on what Sabin's HP is.
What It Does: Restores HP to all members in battle but Sabin. His current HP will be divided among however many people are targeted.
Opinion: This allows Sabin to be used as a white mage. In the battles where you have to divide your characters in three groups and take on Kefka and his soldiers, if you have enough physical attackers, you can use Sabin as a healer with this. Pack a lot of tonics, keep his HP high, and keep healing other members when needed. It doesn't use MP, so you can heal all you want. Sabin isn't the greatest healer in the game, so I use his other blitzes, but he can get the job done with this. Additionally, this blitz can be used as an attack against undead enemies. If you have it by the time you get on the Phantom Train, you'll be in pretty good shape.
Blitz: Air Blade/Razor Gale
Learned: Level 30
Type: Magical, Wind
What It Does: Casts wind elemental damage to all enemies.
Opinion: This blitz is a lot like Fire Dance. I'd still use Fire Dance on enemies that are weak against fire, but this is a nice blitz if the enemies are weak against wind attacks, you're unsure of what the enemies are weak against, or if it's irrelevant, as Air Blade is a stronger attack. Because it's like Fire Dance, I use it the same way. Weaken enemies with this so the rest of your party has a better chance of taking them out.
Blitz: Spiraler/Soul Spiral
Learned: Level 42
Type: Magical, Healing
What It Does: Takes out Sabin to restore HP and cure all status ailments for all party members.
Opinion: This is the ultimate white magic blitz. I guess it's beneficial in boss fights if you're using Sabin as a secondary attacker and healer, as he will completely restore your mains. If Sabin is your main attacker or only healer in your party though, I would not use this as it permanently takes him out of the fight. I personally never use it as Sabin is always one of my mains.
Blitz: Bum Rush/Phantom Rush
Learned: Level 70 or Duncan's House
What It Does: Massively damages a single enemy.
Opinion: This is Sabin's ultimate blitz. It's not always a one-hit kill, but it is near-fatal, and it does not miss. I use it on enemies with high defense stats, as it fairs pretty well.