A few minor typos in artifact activation

[bron]

I ran encountered a typo in the message given when I activated an artifact, so I went through the file, and found a few more. Here are the ones I found with typos in their activation messages:

The Jewel Evenstar:
"Your cloak glows ..."

The Mithril Shield of Gil-galad:
"Your Sheild ..."

Great Axe of Eonwe:
"Your Greate Axe ..."

Mattock of Nain:
"Your Spear ..."

[Magnate]

I fixed this in trunk (r1279).