In addition to Sword of Vengeance, we might also want to look at Nim Deathmantle. Both are amazing equipment.

I'd rather have a Sword of Vengeance out than a Behemoth Sledge (except for when I'm low in life). It's very easy to compare them side by side. Both cost three to play and three to equip.

Sledge - +2/+2,. trample, lifelink - That's great! It's a great card.
Sword of Vengeance - +2/+0. trample, first strike, haste, vigilance

Compare - both give trample, and both give two in the front. The differences:

Lifelink and 2 defense
First strike, haste, and vigilance

Is the defense as important if I have first stirke? Getting in a extra hit with my creatures by equipping them with the sword each time I play another is great. Vigilance is a great ability in multiplayer, the creature stays around. How often do you fail to attack with the Sledge creature because you need to keep it back as a blocker?