Dual Spec Confusion, Help!

Hello I am a new player and just decided to browse the forums for the first time today. Since I started ive been pumping str and dex from time to time. But after coming to the forums I am seeing post of dual specs and also even "bowbears" which use archer weapons and gears. My questions are what the purpose of doing int for bear and wearing caster gear? or using bow weapon with dex? I may sound like a complete noob to sum but I am very confused seeing as tho I assume all our skills were for melee?? And another question would a caster be able to use mage skills with a sword/shield?? or a archer use archer skills with wand??

The purpose? The purpose seems to be to have fun trying new things.
Each class has its limitations. Like an enchantress might have problems in Alien Oasis 3 because they get one-shotted by some of the AoE damage. So instead this person decides they'll make a bear, but give it INT and let it use wands instead, and bam... it survives that AoE.
Or the other way, it's an enchatress who can't stop pulling aggro. so what they do is say "Hey if I have this much threat, I might as well tank" so they respec for all kinds of STR and a little DEX and now you have the "paladin" build.
Dual-specs are usually PvP twinks. That's the kind of thing where they're able to change specs without respeccing, because they have gear with enough stats on it to allow use of other gear in the spec set. So let's say they're balanced between INT and STR as far as where they've placed their points, yet they're still able to wear a bunch of appropriate-level STR gear that feeds itself with +STR, or a bunch of +INT gear that gives them enough int to wear other INT gear.

Okay I see it allows for versatility in certain situation and new gears. But even if they make a bear and give it int won't it still die due to the lack of str that would be given to int instead to use that wand? And what about the skills? Would the bears attack skills still be useable with that wand equipped or a bow maybe?