GameBanshee Forums

Really what is the purpose of being Dual class fighter while when wearing strong armour you loose your skills (mage or thief)? And the best think is that you cannot change armour while in combat!

Well, the whole point of dual-classing is to give your pc (or npc) other abilities. But there are certainly downsides, as you yourself mentioned. I've never dual-classed my pc, dual classed Yoshimo only once.
Dual-classing in BG1 is easier, you don't have to wait so long for the first class to get active again.

Well

The benefits of dualling even a vanilla fighter to mage would be:
Easily more than 2x the hitpoints of a single class mage
Way better base THAC0
Can use practically every melee weapon
GM proficiency possible in most any weapon
Can use bows
Can wear helmets & shields

The armour limitation (other than the general grooviness of the Kensai kit) is why so many choose Kensai/mage when electing to dual class.

For fighters dualled to thief
Better HPs
Better THAC0
GM proficiency possible in most any weapon
Dual wielding is actually a practical option
Can use longbows, helmets & shields

The better leather armours are not so much worse than plate that the AC penalty is prohibitive.

In both cases, even without ToB or an XP cap remover, a fighter of moderate level (say, 9) can dual to either class without significant restrictions on their development potential as a mage or thief

Does that anwer your question?

Not to mention high lev abilites - fighter/thief with avoidance , assassination...

Armor isn't really a problem for dualed fighters. The idea is to kill the enemy before he hits you, so you want to maximize offensive rather than defensive capability. And, as mentioned above, there are other options for defense if you really need them. And, if the fighter is dualed to mage, stoneskin and mirror image completely absorb a certain number of hits.

However, one thing that hasn't been mentioned is that only fighters or clerics can use shields. Thieves are limited to bucklers and mages can't use them at all. So a dualed fighter that wanted to maximize defense rolleyes: ) could use a +4 shield and a single-handed weapon.

Or, he could just hide under the bed and call his mommy...