I made a Spirit sword using the runes: Tal + Thul + Ort + Amn, but for some reason this is broken in Single Player. I do not know Blizzard's reasoning behind this, but I consider this a bug.
Luckily, there is a simple solution. Install a mod that enables ladder-only rune words.
I was not planning on installing mods originally, but in this case, I had already spent the runes. I see no reason why it should not work in single player.
To fix the problem, I downloaded a patched patch_d2.mpq somewhere from the internet, and replaced it with the one in Diablo's installation directory. Usually this will be Program Files (x86) on a modern computer.
After installing the patch, my Sword automatically got turned into the Spirit rune word:
After going through all that trouble, I ended up not using the Sword in combat, since it felt like it was worse than my Malice sword. I used it temporarily to boost my Warcries instead, and then I sold it when I found a +3 Warcries spear to replace it.
It just shows that some of these ladder-only rune words are quite bad :-D
Voice of Reason, Ladder-only
Later, I created a Voice of Reason Sword, and it was a really good choice.
The Cannot Be Frozen part prevents you from getting frozen (usually). I have noticed a few monsters will still be able to freeze you, though they are rare.
Maybe due to some aura, or due to their death explosion. Not really sure. Nevertheless, might be a small bug.