Aeglos:

The spear of Gil-galad. In Sindarin, the name means Snow-point.

Andúril:

The sword of Aragorn. Andúril was reforged from the shards of the Sword that was Broken. It was reforged during the War of the Ring in the year 3018. The name means West-brilliance.
The Sword of Elendil was forged anew by Elvish smiths, and on it's blade was traced a device of seven stars set between the crescent Moon and the rayed Sun, and about them was written many runes; for Aragorn son of Arathorn was going to war upon the marches of Mordor. Very bright was that sword when it was made whole again;the light of the sun shone redly in it, and the light of the moon shone cold, and its edge was hard and keen. (LOTR.294)

The Arkenstone:

A jewel found in the Lonely Mountain. The full name was "The Arkenstone of Thrain".

Angrist:

A knife forged by Telchar of Nogrod. It was so sharp it would cleave iron like butter. It was with this knife, taken from Curufin, that Beren cut a Silmaril free from Morgoth's crown. Beren tried to free a second Silmaril though, and Angrist snapped.

The Hobbit
The Lord of the Rings
The Silmarillion
The Complete Guide to Middle-Earth by Robert Foster
The Unfinished Tales