In player vs player mechanic blocking incoming attacks from arrows blocks all the missile damage including fire or lightning damage from elemental bows.

This looks incorrect to me. If you block the arrow, you can't possibly block the damage from the fire or lightning effect because you're already in the middle of a blocking animation.

In contrast, when blocking incoming melee attacks from weapons with fire and lightning damage the elemental damage does not get blocked.

This is true, and the main difference here is that the elemental explosion from melee weapons gets multiple collision checks, whereas the elemental explosion from arrows only does one collision check against the target the arrow collided with. So perhaps what you are observing is that a blocked arrow is significantly more likely to do no damage compared to a blocked melee attack.

... I personally would advocate for allowing the elemental damage to be universally blocked.

The good news is, this is how it already works. If the player gets hit by an arrow and doesn't go into hit recovery, they have an opportunity to block the elemental explosion, and the effect doesn't do multiple collision checks. If the player dodges a melee attack, they have an opportunity to block the elemental explosion, and the explosion will be deleted upon collision with the player's shield... Except in Hellfire, where the missile just gets rotated. >_>

The bad news is, it's unclear whether I should close this issue or not. It feels like you're horribly mistaken about how these effects work, but it's true that we might be able to tweak elemental explosions from melee weapons to prevent multiple collision checks. Is it still a valid complaint, given the discrepancies I've pointed out so far? 🤷

I'm going to go ahead and close it as completed. If anyone feels differently, feel free to comment.

After our discussion it was agreed that the focus of this issue should be to move the collision check in AddWeaponExplosion() and DoAttack() to decide whether to apply damage to the explosion or not and prevent the multiple collision checks.