How it would work againts Trojans T3 gremlins and alpha wolvers or Roarmulos twins.
Alpha wolvers, not necessarily a problem; it's not a gun, so it wouldn't force them to teleport. If they do, the lock-on would be lost, so it'd just teleport the user forward a couple spaces. Trojans and gremlins would be a minor problem or a boon depending on how the player uses it - a player that spams the combo will suck against both, a player that makes intelligent use of it will use it to get to their vulnerable side. Because it's not perfect for them, it helps as a balancing feature. The Roarmulus Twins, it would just turn the player around between attacks as they can't teleport behind a monster that has no space behind it - but it's a piercing or shadow weapon by design, so it's unlikely a player would choose to use it there anyways.

Plus attacking and teleporting, fooling and evading the enemy seems too powerful.
It wouldn't fool enemies; once they're aggro'd they always know where you are (true for all enemies). If there IS a confuse status it can cause, then confusing them would be part of the point. I stated the third hit would teleport you back to their front, which would make the basic combo not much different in use from attacking twice and then shield-bumping, or attacking three times and hoping you cancel the enemy's attack. It's also somewhat balanced by being very hard to hit multiple enemies with by design, as well as certain enemies throwing the user off (Trojans; Gremlins as you mentioned). Poor use can also throw the user into more danger - teleporting behind a monster and directly into the attack range of several others, or teleporting into traps, for example.

Also balance-wise comes a strong point - if it's fun to use, OOO will balance the damage to make sure it's fair on other players; fun gameplay matters a lot more than high damage to a lot of people. Damage can be made suiable regardless.