Snipers:
Many players that I have played this game with seem to play sniper for a number of reasons. One of the more unknown reasons they play sniper is because they can attack other players from greater distance with enhanced aim which by itself is not unusual . When it starts to become unusual is when they play because they realized that they are a small target to shoot at while their target thanks to their scope is a much larger target to hit. So in this game with the damage afforded to the sniper rifle is very high. So lets look at this closer. In reality a sniper has to take into account many things to make a successful shot and hit their target (examples: wind speed/ direction, target movement, TTT (time to target/distance), breathing control, re-chambering of a round for a missed shot, noise of the shot being detected, muzzle bloom (fire), etc) these of course are not in this game. The only things that are retained in this game is the damage (to a point), the enhanced aim, and presenting a much smaller target to your enemies.
So where am I going with this ? Many of these real life things are left out for a more simple and streamlined game play. So for the sniper what I propose is this to keep this game even . Since the sniper presents a much smaller target to shoot while retaining an aiming advantage make it so any returned fire (regular gun fire not abilities) that hits the sniper mirrors the damage of their own rifle with the same headshot modifier.
Phantom:
Melee ghost known as Phantom enjoys technology that is not yet available to combat soldiers in that he can become invisible and to some thanks to an audio glitch makes no sound either while cloaked (this may be fixed sometime). Now we know that invisibility of this type is not realistic (yet?) in this day and age so it allows for some leeway when it comes to tuning this major advantage and allowing for counterplay to this that is even the power of first shot on a target. The technology employed to make phantom silent (maybe?) and invisible comes at a cost to personal protection in that his hit points while cloaked before that of half that of the lowest light armor merc. This would allow for the same amount of risk of being hit as doing the hitting from a advantaged position. Now I know what many would say about this , "what about Phantom going against medium and high armor target players and not having the speed of a light armor in close combat maybe a sort of melee aimpunch added to his melee attack? This would of course need to be monitored closely to ensure that it did not removed the risk of getting that close hit on the more armored and therefore slower target.