[Kaleban]

Any class can be soloed at any difficulty, the question is merely of patience and skill on the part of you, the player.

All warriors get an extra 1/2 attack at level 13, and a Kensai's abilities by level are given at every 4th/3rd level, so dual at either level 12 or 13 depending on how much you want an extra 1/2 attack.

Dual or Multi depends on your style. An Elf multi will be hard to charm and has Infravision, Dwarves and Halflings are resistant to poison and magic.

Probably the easiest solo class later on (initially can be difficult) is the Sorcerer. Very versatile, and VERY powerful with the right selection of spells. F/M/Ts are also versatile, though their long-term power is limited as they gain levels slowly even soloing, and their extreme versatility limits their maximum power.

Hope this helps you out!