In the old legends of the Middle East from where they originate, the Magus, or Magi, are students of the arcane who also study other arts such as the sciences, astrology, and alchemy. They were overall students of knowledge, which is perhaps why the word Magi tends to conjure the idea of mystery, knowledge and wisdom in the minds of people when they hear it.
The word and ideas being the Magus are used in a variety of fantasy settings, usually as a kind of magic user with skills beyond the normal arcane. In fact, the word "mage" is pretty much an Anglicization of the old Roman "magus."
Since the term "mage" is irrevocably associated with wizards now, the Pathfinder magus is completely different from its source material. Magi are students of the arcane and the martial arts at the same time, bending spellcraft and weapons work together into a fusion deadlier than its parts - essentially a Duskblade but with fewer spells and some of the higher-level stuff available as starting character, or a reworked Swordmage. Many are wandering travelers seeking mystic and material lore to further improve their skills. Mechanically, they get three major advantages: the ability to cast arcane spells in light armor (with the weight class going up with higher levels), an ability called spell combat, which is essentially two-weapon fighting but with the off-hand weapon being a spell the magus casts, and an arcane pool, a resource the magus can spend to make different special abilities go off.
Spell combat is powerful and versatile, and it only gets better as they level up. It lets them put up a shield spell before whacking you, or shoot a fireball at you from outside the blast radius before charging into melee. It keeps getting better: as early as level two, they can also deliver touch attack spells through their weapon, giving them a free extra damage roll if the spell hits. And any spell you cast in this way crits when your weapon does, which, if you sprung for a high-crit weapon like a scimitar or urumi, can get ugly fast. (Protip: Shocking grasp is almost too good for a first level touch attack spell already, and the "Magical Lineage" trait lets you metamagic it at a reduced rate, while the arcane mark cantrip never gets used up and explicitly permits the second attack as per a FAQ. Also, because touch spells only go off when they hit or you "drop" them, always lead with your spell rather than your weapon attack. That way, you get two chances to get the spell off instead of one.)
The arcane pool, meanwhile, is a pool (HA!) of resources not unlike ki. Points can be spent to boost attack and damage rolls, or to activate various other arcana gained by leveling up, like swapping out prepared spells or suddenly learning new ones.
"So far, so good," you might be thinking. "Sure, this class sounds like a hideous amalgamation of every other D&D class ever made, but it also sounds fun and powerful." Well, hypothetical reader, you're right.
"But is it as powerful as a wizard?" screams the bloody-handed munchkin, scheming some way to have his constructs make other constructs that cast infinite numbers of wish spells for more wish spells so that he can literally get whatever he wants whenever he wants.
Of course not, you schmuck. Magi are tier 3, able to a variety of things well, but none so well they invalidate challenges. They gain fewer spells more slowly than wizards, but still rely quite heavily on janking spellbooks. They never get high-level spell slots either, capping out around the sixth level. They will never be able to break game balance like a twig, then don their robes and wizard hats to fuck its corpse quite like a wizard, and they don't get full base attack/feat progression and independence from any kind of resource exhaustion like a fighter. They aren't as narrowly focused as either. Hell, one can't even call them the ultimate "jack of all trades" class, as that title is also already taken.
What they do have is a unique twist on the arcane caster style, and a very fun and unique way of playing the game. Magi aren't fighters and aren't wizards, and trying to play them like either will leave you the impression they suck, because they need to be played like magi to be effective.
Magi get access to some pretty cool archetypes too, most porting over some aspects of earlier classes and kits from previous editions, and unlike some Pathfinder classes, many of them are stackable. Being a bladebound magus trades in a few low-level class features for a sentient magical weapon buddy with cool powers who may or may not end up backstabbing the poor sod for its own agenda, the kensai loses all of their armor and one of their spells per level to gain tons of cool weapon powers and the addition of monk-style unarmored defense (which is close enough to the spirit of the original kensai to be forgiven the addition of spellcasting), a hexcrafter gains access to some cool new curse spells and witch hexes (like its cousin, the hexblade), the mindblade basically amounts to a soulknife that doesn't suck quite as much, myrmidarchs basically trade in half their class features for fighter ones, you can go the fluff route and basically be [Gambit] complete with [quarterstaff] etc. All of them have a lot to offer, both mechanically and flavor-wise, and almost none of them are flat-out better than the base class.
Similar to witch hexes, oracle revelations, alchemist discoveries, fighter bonus feats, and the like, the magus gets a magus arcana every three levels. One of them is called "Bane Blade", which is awesome.
|The Classes of Pathfinder|
|Core Classes:|| Barbarian - Bard - Cleric - Druid - Fighter - Monk |
Paladin - Ranger - Rogue - Sorcerer - Wizard
| Alchemist - Antipaladin - Cavalier |
Inquisitor - Oracle - Summoner - Witch
| Arcanist - Bloodrager - Brawler - Hunter - Investigator |
Shaman - Skald - Slayer - Swashbuckler - Warpriest
| Kineticist - Medium - Mesmerist |
Occultist - Psychic - Spiritualist
|Ultimate X:||Gunslinger - Magus - Ninja - Samurai - Shifter - Vigilante|