are gems just for selling or can i do something else with them(i think not but i want to be sure)
one more thing, i wanted to know which swords(long small bastard great)is the best

Gems are just for sale. If you are playing with a Paladin go for the long sword(Holy Avenger) I usually have my Rangerx/fighter4 dual wield a bastard sword and a long sword or scimitar.

Gems are a source of cash. That's it. The later you sell them in the game, the more they are worth. But then, that late in the game, you will be finding weapons which are so excellent, there just isn't all that much need to buy them. If you buy weapons from Kuldahar on, you might get some that have nifty little extras to them, but nothing that will just bolster your fighting ability 100%. Hence, I sell gems as soon as possible and use the cash. +1 bullets and arrows, start game, really come in handy when you're low level and can use the Thac0.

Endgame, a two handed weapon (with high strength, mind you) is the best. Lots 'o damage, and by then your level and Thac0 is high enough to actually hit something. Beginning of the game, with low level monsters, you'll do marginally better with dual-wielding.

All that depends on your character, though. More dexterity than strength (like, 18/14), dual-wield the whole game. More strength than dexterity (like 18/14), either one handed or two-handed weapons. Also, it's in everyone's best interest to keep at least one blunt weapon and one slashing/piercing weapon in their inventory. Some things respond better to blunt, and some are a little more vulnerable to mincing.

Just to expand a bit on ejsmith's post, if you are high on dexterity and low on strength, not only are you better off dual-wielding, but you are better off dual-wielding light weapons with the weapon finesse feat.

Short swords only for dual-wielding and high dexterity builds. You put everything in DEX instead of STR, choose weapon finesse, get a ranger level for free dual-wielding without heavy armour one and you're ready to dual 2 short swords without penalties. DEX and heavy armour AC bonuses don't stack (apart from max +1 DEX bonus for full plate), so you don't lose anything.

Longswords and scimitars belong to one cathegory, longswords. The former deal more damage, the latter score critical damage more often.

Bastard swords are supreme damage delivery device among one-handed weapons - and they allow shields. No class gets any proficiency in bastard swords at start.

Two-handed swords - greatest damage, extra range, 1,5 STR modifier. Shields, of course, aren't allowed here.

Something that always confused me was how come we could never be able to use a buckler with say a spear or 2-handed sword? Don't bucklers just tie onto your wrist?

:yot:
Talking about bucklers, do they have any advantage over a small sheild?

to griffin1987:

Yes some types of defensive devices are mounted to forearm.

We should see bracers as these devices. They provide some defense and they don't hinder movement.

Of course there could be "mounted bucklers". But use bracers instead.