I think seeing the enemy's HP, uber, targetid, favorite color, and social security numbers is a bit op as it stands now which is probably why it's been banned since the get go. I'm proposing a change to it completely:
When EQUIPPED, the Solemn Vow has a permanent hud element to your screen next to your current ubercharge percentage that shows the -/+ advantage of the enemy medic.
When ACTIVE, it reduces your movement speed much like the Scottsman's Skullcutter does by about 10-15%.
This unlock would accomplish two major things: Makes the game more accessible for matchmaking newbs and increases the pacing of the game tenfold because you're no longer waiting in that relative safety time period where you think they might just be about able to get uber in the time it takes you to push, etc. Map design aside, you'll see a lot less stalemates and more action.
What do you guys think? Is it too much? Does it need a more pronounced downside? Do you like Piña Coladas?
Holla atcha noid