I've been a craftworlder for +15 years, so I would like to see CWE and DE work as they should. All their units.
The main difference between CWE and DE is psychic power (and the lack of it). All craftworlders are psykers to some extent, and most of their gear and weapons make use of that. DE have removed their psychic potential and focus on their physical power and abilities.
If we do not count warlocks, Craftworld Eldar have 3 dedicated CC specialists. We can also extrapolate their DE counterparts.
Banshees are the fastest, armed with power swords to kill armoured troops (MEQ and TEQ) and also with their masks they are able to stun the enemy, so they can counter other CC dedicated troops. Basically they are the doom of elite units, and their masks are their pseudo-psychic gear. Wyches will be their DE version, most probably faster than them (they already were), as they sacrifice gear and even armor to do so, and make use of dodge to counter power weapons. Wyches, in numbers, should be the bane of any dedicated CC unit.
Shining Spears are the knights, the cavalry, a powerful charge and good armor, able to deal with monsters and vehicles (or characters), but not lots of infantry. They also lose power after the charge. They have a psychic connection with their bikes. Reavers are not knights in any way, they're the mad max version instead, they hit fast and leave without giving chance to the enemy to respond. They should be weaker either in attack or defense, gear-wise, than their CWE counterparts, but their abilities should give them what is needed to do the job.
Striking Scorpions are silent assassins. They hunt the enemy from the shadows. Instead of agility, they use strenght, and unlike banshees or spears they can go against lots infantry and win. Like banshees, they have an iconic helmet gear that gives them an edge against their enemies, the mandiblaster. It is also fired using a pseudo-psychic mechanism. This weapon is famous for being very powerful, but it must be fired point-blank. As we have read, it can deal mortal wounds, but these might need a roll of 6+, as far as we know. This kind of power now makes the scorpions more appealing against their competition when making the army list, banshees, that tended to be the first CC choice (as most of the enemies were SMs, the canned monkeighs, and banshees were always known as can openers). Incubi are the DE assassins, but also the bodyguards. They don't hide like scorpions, they are not as fast as banshees or wyches, but they are well armoured and carry the most vicious weapons, and they use them bloody well. So, they are pure killing machines, and if you don't kill them first, you'll be cut in half.