Multi-attack + Dual wield.

[Gix]

It is my understanding from reading PHB that there is:



TWO-WEAPON FIGHTING
When you engage in two-weapon fighting, you can add your ability modifier to the damage of the second attack.
PHB pp72



Two-Weapon Fighting
When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand. You don't add your ability modifier to the damage of the bonus attack, unless that modifier is negative.
PHB pp195

What happens when you have multiple attacks?

So Extra Attack at 5th level for Monk states you strike twice rather than once when you take the Attack action (using strike rather than "attack" to reduce confusion).

In addition spending a Ki point lets you use Flurry of Blows which states that immediately after you take the Attack action you can spend it to make two unarmed strikes as a bonus action.

Therefore:
1. Monk Attacks with sword: rolls twice to hit because "Extra Attack"
2. Monk now has two choices that he can in no way combine:
. . A) Bonus Action: Offhand strike, and swipe with offhand sword, which is rolled normally to hit, but cannot add Dex bonus to damage.
. . B) Bonus Action: Ki -> Flurry of Blows, Two more unarmed attacks (maybe kicks, or elbows, or something)

Do I have that right? Therefore a dual welding monk is kinda pointless if he's going to use Ki points for Flurry of Blows.

What are folk's feelings on letting one of the Flurry of Blows be the off-hand weapon? (It seems situational to me in that maybe at low levels that would be better, but later on Martial Arts will be more powerful in terms of raw dice.

Are there other considerations?

[Zacchaeus]

You are correct that you can't take a bonus action to hit with a weapon and then use Flurry of Blows; they are mutually exclusive. Note that if the Monk is using Monk Weapons (and why would the monk not use Monk weapons) that the Martial Arts ability allows the Monk to make an unarmed strike as a bonus action (without spending ki points). So unless the Monk is doing something else with her bonus action then they'll always get three hits at level 5.

Most Monks I've seen use the Quarterstaff two handed so that out-damages the short sword by quite a bit.

Whether you allow a weapon attack as part of the Flurry of Blows is really up to you. I certainly wouldn't allow it but it is your game whcih you should play the way you and your players want to play it.