Seeking Enchantment (for swords and axes)

What it is:
A seeking weapon behaves similar to Sting in The Hobbit and The Lord of the Rings. It provides player the ability to more accurately detect mobs and where they can spawn from.

How it would work:
The weapon normally glows blue like all enchanted equipment. If the player stands on a block that a hostile mob can spawn on it will glow yellow. This function only counts the light level from permanent light sources like torches, not the sun.

If a mob is within range blocks it will change to a faint red glow.  The glow will be slightly stronger if the player is facing the mob. The glow also intensifies with the count of hostile mobs within range. It can do this through walls.

Seeking I has a 4 block range. II 8 blocks, III 12 blocks and IV 16 blocks away.

Why add it:
Seeking solves two related problems. At home it allows players to accurately mob-proof structures. Note that this can be done in Java already by hitting F3 and checking the light level of blocks - but this existing solution is somewhat 4th wall breaking and some may view it as a cheat.

The second problem is pinpointing the mobs that can be heard through the walls. While dungeons can be tracked down by ear, it's time consuming. Again, a locate command could be used, but that's a cheat.

Finally, having something with a faint nod to Middle Earth would be kinda cool.