The weapon is considered blessed...

[SableWyvern]

The spells Bless Weapon and Magic Weapon (the latter only in the case of certain casters) both have as part of their affect that

...the weapon is considered blessed, which means it has special effects on certain creatures.

(PHB, pp180 & 225)

My questions are: What special effects? and on which certain creatures?

I cannot find this information anywhere, and it is driving me insane!

Please help...

 

[Gromm]

Look in MM under demons/devils/rakshasa.
Individual descriptions of almost any devil or demon should answer the question.

 

[FANGO]

In case you don't want to look it up...

Basically, blessed weapons are to infernal beings as fire is to trolls. A lot of demons will have a note under their regeneration ability that says "...takes normal damage from holy or blessed weapons of +x or greater enchantment." So if you're fighting a powerful demon or devil or something of the sort, it's usually a good idea to have a few of these around. Also, in the case of the rakshsa which was mentioned above, they are vulnerable to blessed crossbow bolts and if they are hit by one they are slain instantly. There may be some other effects like these, but they are usually pretty specific and you can find out by checking MM entries if you're not sure about it.

 

[SableWyvern]

Thankyou very much.

 

[med stud]

I think it is funny that the demons and devils of the Blood War have to use blessed weapons to hurt each others

 

[Henrix]

I think it is funny that the demons and devils of the Blood War have to use blessed weapons to hurt each others

No wonder that war is taking them forever!

 

[(Psi)SeveredHead]

Nah, they just use spells or natural attacks. In the case of natural attacks, if your DR is the same as their DR, then you can scratch them. Many fiends don't regenerate from +3 weapons, so a balor is pretty good at scratching other fiends. Also, the pit fiend's DR is actually +3, not +2.

 

[Henrix]

DR or no DR. A Retriever, for example, Regenerates. It only takes real damage from, you guessed it, blessed and holy weapons.

 

[pontus]

DR or no DR. A Retriever, for example, Regenerates. It only takes real damage from, you guessed it, blessed and holy weapons.

The retriever has Fast Healing, not Regeneration (as per the MM errata, not that most people weren't running things that way before).

 

[Henrix]

True, Pontus! I forgot to check that.
Still leaves us with the Gelugon, though. It might be that he should have been errataed, but he isn't, yet.