Let's say an Eldritch Knight (lvl 8) casts Alter Self and gains claws as natural weapons, could he then create a Weapon Bond with his claws?
Alternatively, could you be a Minotaur race then Weapon Bond with your horns?
Relevant Rules
Melee and Ranged Attacks
The most common actions that a monster will
take in combat are melee and ranged attacks. These can be spell
attacks or weapon attacks where "weapon" might be a manufactured item
or a natural weapon such as a claw or tail spike. (MM p10)
Weapon Bond
At 3rd level, you learn a ritual that creates a magical
bond between yourself and one weapon… Once you have bonded a weapon to yourself, you
can't be disarmed of that weapon unless you are incapacitated. If it is on the same plane of
existence, you can summon that weapon as a bonus action on your turn,
causing it to teleport instantly to your hand. (PHB p75)
Alter Self; Natural Weapons
You grow claws, fangs, spines, horns, or a different
natural weapon of your choice. Your unarmed strikes deal 1d6
bludgeoning, piercing, or slashing damage, as appropriate to the
natural weapon you chose, and you are proficient with your unarmed
strikes. Finally, the natural weapon is magic and you have a +1 bonus
to the attack and damage rolls you make using it. (PHB 211)
Best Answer
Yes, but why?
A weapon in 5e is defined in the basic rules under the monsters section as
The Weapon Bond ritual has the following requirements:
Requires 1 hour
Target must be a weapon
The weapon must be within your reach for the entire ritual
You must be able to touch the weapon at the end of the ritual
So you certainly could bond a natural weapon... but why? You already can't be disarmed of natural weapons, and since they're part of your body, they won't ever be far enough away from you to summon.
As for temporary natural weapons gained from Alter Self, they would disappear as soon as (or just before, depending on interpretation) you finished the ritual, rendering the ritual pointless. The ritual definitely wouldn't allow you to regain the natural weapons as a bonus action; They no longer exist when the spell ends.