PoE Double holding:
Definition: Both hands hold a one-handed weapon at the same time. (One hand weapon and one hand shield are not acceptable. Two-handed weapons are not acceptable.) Applying these mechanics, you can obtain poe chaos orb easily for it increase your speed of killing monsters.
When you hold it, no matter what weapon or what, there must be the following fixed bonus:
1.10% more attack speed
2.15% exceptional attack block rate
3.20% more attacks physical damage
The main thing to note is that although most of the skills are taken by two hands in turn, there are still some skills that are attacked with only one hand. I will list these skills below because they get different bonuses when they are dual-held.
The staff can also be dual-held, but the other one cannot be a one-handed melee weapon.

Master skill: (only one hand attack):
Cracked ground
2. Jumping
3. Frost shock
4. Large earthquake strikes
5. Double strike
6. Ancestors
7. Break axe
These skills are only attacked with the main hand weapon (ie the one on the left side of the weapon bar). Therefore, many attributes of the deputy are not available: for example:
1. Increase XX% physical damage
2. Additional physical, elemental, and chaotic injuries
Hit
4. Attack speed
5. Weapon crit rate...
......

What you can eat is:
1. Increase global physical damage
2. Attack and spell crit damage
3. Global attack speed
4. All attributes, life/blue stealing, replying, lowering threshold, resistance
5. Extra XX% physical damage as XX damage (element)
6. Attach XX% element damage as chaotic damage
7. Double hold XX% block
8. Increase attack skill XX% element damage
9. Increase xX% global hit rate
......

Therefore, it can be seen that all the bonuses of weapons can not be added to the "one-handed skills". Anyone who can cause global influence can give one-handed skills.

Two-handed skills: (two weapons are used in turn):
Hammer of Frost
2. Slam
3. Purgatory Strike
4. Earthquake
5. Broken space
6. Bloodletting
7. Shockwave
8. Viper blow
9. Blade flurry
Please note that this is actually a rotation version of the one-handed skill: when using the main hand, the attribute of the main hand plays the effect, and the condition of the attribute of the deputy hand is the same as that of the main hand when using the "one-handed skill", and the next attack After the rotation to the deputy, it is the turn of the attribute of the deputy hand, and the condition of the main hand is the same as the deputy of the "one-handed skill".
So in this way, hits, crit rate, attack speed, and so on, are the average of the two weapons.

Even if you use only one weapon, these skills will also have a fixed bonus of double holding.
Randomly select a weapon to attack:
Swiveling blade
For details, please refer to the above "two-hand skills".
Synchronization skills (both hands swing at the same time, instead of the main hand deputy take turns):
Cut
2. Double holding
3. Blade