As a monk, you have the ability to make unarmed strikes as a bonus action, which can be a powerful tool in combat. However, if you want to wield a single-handed weapon, you may find that you cannot use your bonus unarmed strike action. Fortunately, there are several solutions to this problem.
One solution is to use a different weapon that is typically wielded in only one hand, such as a short sword or dagger. This would allow you to use your bonus unarmed strike action while still having a weapon in your off hand. This can be a good option if you want to maintain the versatility of using both a weapon and your unarmed strikes in combat.
Another solution is to use a weapon with the "Light" or "Finesse" property. Weapons with these properties can be used one-handed even if you are also using your bonus unarmed strike action. This can be a good option if you want to use a specific weapon that is not typically wielded in one hand, but has the "Light" or "Finesse" property.
If you are looking for a more permanent solution, you could consider multiclassing into a class that grants the ability to use weapons one-handed, such as the Fighter or Rogue. This can be a good option if you want to focus more on using weapons in combat, rather than relying on your unarmed strikes.
Finally, you could simply use your unarmed strikes as your primary attack, relying on your martial arts abilities and bonuses to make up for the lack of a weapon. This can be a good option if you want to focus more on using your unarmed strikes, and are not as concerned with using a weapon in combat.
In conclusion, there are several solutions to the problem of wielding a single-handed weapon as a monk with a bonus unarmed strike while avoiding using a two-handed longsword. Whether you choose to use a different weapon, a weapon with the "Light" or "Finesse" property, multiclass into a class that grants the ability to use weapons one-handed, or use your unarmed strikes as your primary attack, there are many options available to you.
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