Classes

The assassin is actually the class dealing out the highest amount of combat damage but is relatively fragile. Assassins are masters of hiding and using stealth, but have little skill in lock picking.  They have lower end magery, but will be able to cast from scrolls with a bonus.

The bard on Valhalla is a well-blended adventuring class.  While a bard can only truly master the art of music (and breaking into things), he is well above average in all of the combat skills and magery as well.  

In combat, clerics and priests could be compared to a tank mage.  They can wear strong armor, and are masters of both the mace and the spell book.  Furthermore, they are unparalleled in the healing arts.  The primary difference between priests and clerics is the way that they are role played.  The Cleric is a virtue follower, while the Priest tends to focus more on a divinity.

The nukers of the game, designed for massive spell damage but quite fragile.  These classes need to learn to stay out of the way, letting their skill in magery do the trick while letting better suited warriors hold off their targets.

Druidry and Necromancy are directly opposing school's of magic. The use of one will always detract from the other

The fighter is a master of all forms of physical combat.   Fighters can do everything - Archery, Fencing, Macefighting, Swordsmanship and Wrestling.  They are also above average healers and tamers.

Second in combat skills only to the fighter, a knight is a warrior to be reckoned with. In addition to superb hand-to-hand skills, knights are the most respected leaders in the land.

Mages understand their art better than anyone else, including necromancers and druids.  In addition to being only class that can use every spell in the regular spellbook, they can also reach a higher skill level in magery than anyone else.  Mages may also master a weapon, are one of only two classes that can gm alchemy and are above average healers. 

The paladin is the premier religious fighter, with strong healing in addition to some magery and meditation (may have a limited spell book but is able to cast from all scrolls).  The Paladin's focus is first on battle then on healing.  They don’t get as high a skill in leadership as the knight or as much healing as the cleric, but are a very strong class all around.

A ranger is the premier archer, supported by taming, magery and either necromancy or druidry. In addition the ranger has some unique abilities to track, point and restore a weary group.

The thief is not a great group player, there's now way to change that, but between their locking picking skills and limited bard songs, they should be welcome in a group. Give a thief mining and cartography and you will have an awesome treasure hunter.

The traditional tamer of UO, but with decent magery and excellent healing for both people and pets.