A simple bit of guidance that has served me well on many a battlefield: poncy Dark Eldar Lords should avoid thick jawed, heavy armoured, low intellect instagib specialists.
This will not end well...
Dark Eldar are an army of piratical raiders. Using them well involves striking where the enemy is weak and applying your full force against part of theirs. That's the fluff and that's what we do best.
The above is why I am mystified by constant complaints about Huskblades going to AP3... If you were charging your Archon headlong into squads of Terminators on turn 2 then you have chosen the wrong army. In the fluff, an Archon arrives in their position as much out of political astuteness as their abilities in combat. In the crunch this is well represented through their t3 & 5+ armour save.
We have all had Lelith Hesperax slice through a Combat Squad only to receive an autocannon in the face. It is all part and parcel of being Dark Eldar.
If you just want to froth at the mouth while running various beatstick HQs blindly in the direction of the nearest enemy, try the Early Learning Centre option of Space Marines (or use Drazhar).
For the Emporer!
When you could rely on Fortune from an Allied Farseer (i.e. pre 2013) dancing with Terminators was maybe possible (although very cheesy). This is no longer the meta . Randomisation is the new black; this means relying on things that you know you can do well with drugs/psychic powers etc. as an extra boost (unless they are Primaris).
An AP3 Huskblade is not something I will use in all likelihood. For my money the newly poisoned Agoniser is probably better (depending on points cost). But both will serve admirably in dicing Tac Marines / Fire Warriors / Guardsmen (the sorts of things you should throw an Archon at).
Let the opponent deep strike his Terminators and then run away from them. While they're slogging 6" a turn across the board, zoom away with glee and pick them off with Splinter / Dissies / Ossefactors or well placed insults. Maybe let your Archon swoop in to clean up the last couple and claim the glory once he's mulched a few captains to feed his Soul Trap. But only maybe. And probably only as a last resort.
"And I was like OMG die you Imperial Terminator Scum!"
"And then he was like s8 Powerfist Bitch"
"And then I was like... wtf even is that gtfo. I need a regen booth :("
There are loads of reasons to be optimistic about the new book. So don't let lobotomised neck-beards and thirteen year olds get you down. I have played through 2.5 codexes and 2 decades of Dark Eldar. I am more optimistic about this release than any other before it.
I will be posting tactical advice here over the next few days to help ease your transition into the new codex. Check back and keep your head up fellow Dark Kin.