So I know that 1h+shield with flametongue weapon is the most efficient. But if I got a shit 1h and a really good 2hander (before lvl 30) should I still use flametongue or should I use frostband or rockbiter instead?
I pretty much have no other option than give you Melderon's Shaman Guide.
Both https://classic.wowhead.com/spell=8038/frostbrand-weapon#see-also-ability and https://classic.wowhead.com/spell=8030/flametongue-weapon are affected by spell power (10%, someone correct me if I'm wrong - with source), however, at low levels you won't have any. That being said, you can do some quick math and figure out the PPM (proc per minute) or proc rate of your effect on a weapon.
Remember, Blizzard never released any specific number, so this is a number that has been "reversed" by other players.
You have a 2.0 Attack Speed weapon. Multiply 2.0 by 15 = 30. You have a 30% chance to proc whatever is in your hands.
The slower the weapon, the higher the proc chance.
You have a 3.6 Attack Speed weapon. 3.6 * 15 = 54% chance to proc.
From here you can compare damage between, we'll say: https://classic.wowhead.com/spell=8038/frostbrand-weapon#see-also-ability and https://classic.wowhead.com/spell=8030/flametongue-weapon
We'll guess and say https://classic.wowhead.com/spell=8030/flametongue-weapon (Rank 3) deals an average of 15 damage a hit. Because it's guaranteed, your 2.0 attack speed weapon deals 450 fire damage every 30 attacks, or 450 per minute.
Now, https://classic.wowhead.com/spell=8038/frostbrand-weapon#see-also-ability (Rank 2) on your 2.0 has a 30% chance to proc. That means, at 30% chance to proc - you'll proc 9 times every 30 swings. This means your 2.0 attack speed weapon will deal 477 damage every 30 attacks, or 477 per minute. Or if you're lazy and want a less statistical answer, (.3*30)=9.
It just depends on your weapon. My two 
on the matter? Paladins rule, Shamans drool.
It just depends on your weapon. My two on the matter? Paladins rule, Shamans drool.
Very interesting, and I really enjoy Paladin so I can't contest that hehe.
Nenski
What exactly is the point of calculating proc chance? The whole idea of ppm is to normalize damage against different weapon speeds.
Multiplying ppm with the on hit damage allready gives the dpm.