Common Myths

Myth: Arrow Blow is better than Double Shot

Arrow Blow does less damage than Double Shot, as it only has one chance of hitting critical.

It should be noted that most people don't understand how this works. Critical does +100% damage; not x 200% damage. This is a very big difference in AB vs. DS damage calculations. If AB gets a critical, it does 260% + 100% damage, or 360% damage. If DS gets 1 critical, it does 130% + 130% + 100% damage, or 360% damage. If DS gets 2 criticals, it gets 460% damage.
Similarly speaking, Arrow Blow does not "armor break". That is; DS and AB take in the same amount of armor from the enemy. For example: Iron Hogs may remove 300 damage from arrow-blow, but it will only remove 150 damage from each double shot. It has been tested; and the amount of armor removed is proportional to the % damage. So Power Strike, which does 260% damage, will take in 260% more armor than a normal hit. Same with Arrow Blow, Double Shot, final attack. The only attack that this may not work with is Arrow Bomb, PKB, and "Spread" Final attack on warriors; but tests in this area have been too few and no conclusion has been reached yet, as the damage formulas for these attacks are unknown. Note: When you do a critical shot with AB, the "armor" value is 360% higher than normal.
With these two facts; it is easy to see that DS will always do at least the same amount of damage as arrow blow; add in the critical damage, and DS does an average 12% more damage than Arrow Blow. Arrow blow is only better in the few cases of "flinch", aka "KB" or knockback. If you don't know what I'm talking about, shoot a few shots at Stone Golems, and notice they can only be "flinched" if you do 1000 damage.
Arrow Blow DOES have an advantage over Double Shot, in that it's damage per MP rate is 21.4%/MP, higher than the damage per MP rate of Double Shot (21.25%). However, the advantage is VERY slim, and the advantage of being able to kill monster faster outstrips the damage/MP rate by at least 10 to the exponent of 10 times.

Myth: Arrow Blow is just as good as Double Shot because of knockback

The only monster where knockback (KB) will matter is Cargos. At taurospears/tauromacis, they charge lightning even if you KB them. Zombies is same thing. Golems are too slow. Yetis and Yeti/pepes are slow, and Earthquake will still hit even if you KB them. DS will KB every other monster.

[NOTE] While arrow blow is weaker than doubles hot in terms of damage, its knock back ability may also be insignificant, it must be noted that double shot will be completely replaced by strafe while arrow blow retains some use. If you choose arrow blow, you will suffer the less damage but eventually have an greater array of skills.

~ You can always skip focus and get Arrow Blow anyway, and if you don't get FA then you have the points to finish it later.

Myth: I only need 15 Bomb/IA or 10 DS/AB

30 Bomb or IA is MUCH better than 15 bomb/IA. Additionally, the money "saved" in mana pots is near nothing compared to the money you will spend on your equipment, which will be many millions at higher levels.

Myth: I only need 19 mastery

This was commonly told in older guides, because the only bonus gained from level 20 mastery is 1 accuracy, which is useless for archers. However, it is now a prerequisite for the 4th job skill (Cross)bow Expertise. One could also max it later with one point from 3rd or 4th job, but this would be a poor waste of SP.http://strategywiki.org/wiki/MapleStory/Bowman_Guide/Builds