Chaz Ashley is an energetic youth, just 16 years old, taken under the wing of the famous Aiedo Guild Hunter Alys Brangwin. The two of them begin their quest in Phantasy Star 4 in the town of Piata. Something strange is occurring in their home planet of Motavia, with the depleting resources and the bio-monsters roaming the land.
Chaz starts off weak, but soon you can tell he is going to be the hero swordsman of your group. His skills in particular are devastating, with Crosscut being a premiere attack for a good portion of the game (until he gets even better skills like Rayblade. His attacks generally take off the most damage, or up there with Rune's spells. And he gets the most powerful weapon in the game much later on.
That is not to say that Chaz is imbalanced. He has some mediocre healing spells, decent speed / defense, and has HInas and Ryuka to teleport out of dungeons and around the world map. This is good since his magic is often times neglected (though his Tsu / Thu magic can be serviceable in boss battles when he runs out of physical skills).
Chaz won't be using shields. He could equip a knife and a shield, but it is pointless with how powerful the Swords are in this game. Swords however require two hands so he cannot hold a shield.
Earth - Chaz starts off with this crappy skill. It can paralyze an enemy for a few turns or at little as 1 or 0 turns. It is not worth your time to use this skill, just attack.
Crosscut - Crosscut is where it's at. This is easily one of the top skills early on for any character, doing around 2x damage with 100% hit rate. Chaz does not start with many charges of Crosscut, so save it for when you really need it (bosses, or tough random fights if you really have to). Chaz learns this skill on level 6 and it will be useful for a long, long time.
Airslash - Learned on level 13 by Chaz. This attack does no more damage than a regular Chaz attack, but it hits all enemies with 100% hit rate. Thus, it is a useful skill to use when fighting multiple enemies, but not really worth using against bosses.
Rayblade - Chaz doesn't learn a skill for 14 levels after Airslash, but once he hits level 27 he gets a really nice skill. Rayblade does between 300-400 damage on any given enemy, with extra damage to undead enemies - quite a few in the Dezolis and later areas. This skill absolutely needs to be saved for boss battles, some of the later ones being awfully difficult, and every last Rayblade will help. Upon getting this you can start to spend more Crosscuts in normal battles, but you will still want to keep a few of them packed away for when Chaz runs out of Rayblade in boss battles.
Explode - Watch Chaz explode. This is an odd skill. Chaz basically becomes one of those Float Mines that you have fought in the past, and kamikazes his way towards an enemy. It works on both the mech-types and the Bio-Monsters, but it's usefulness is limited. You get it so late, not to mention you have but a few uses of Explode. Still, something to remember if you have a tough regular enemy you would like to kill instantly.
Res - starts with this technique.
Tsu - Chaz learns this at level 4.
Hinas - Chaz learns this at level 8.
Ryuka - Chaz learns this at level 9.
Anti - Chaz learns this at level 11.
Zan - Chaz learns this at level 12.
Rimpa - Chaz learns this at level 14.
Gires - Chaz learns this at level 16.
Githu - Chaz learns this at level 17.
Brose - Chaz learns this at level 21.
Gizan - Chaz learns this at level 23.
Rever - Chaz learns this at level 24.
Nathu - Chaz learns this at level 31.
Nares - Chaz learns this at level 36.
Nazan - Chaz learns this at level 37.