Not an ultra noob question at all, it's just a misinterpretation brought on by how they've (poorly) organized the new format of the codex.
The melee weapons section you're likely looking at is near the end of the book and has long descriptions of equipment but no points values, correct?
When it says on the Archon Datasheet (p.70) "Melee Weapons" list, it refers to the lists as write on p.69 of the codex, "Dark Eldar Wargear List".
And sadly, the only wargear on the Melee Weapons list are the Power Sword and the Agoniser.
That Dark Eldar Wargear List is where you've gotta go to look up who can take what. The descriptions further in the book refer to rules for different weapons and have them lumped by style to make searching easier, but that section doesn't say who can take what.
I dedicate these deaths to Odin Allfather, Spearshaker, One Eye.
Fleet Shadowmaker - Kabal of the Dying Sun; Cult of Marrow Excised; Coven of Lambent Hunger
Sons of the Last Breath - Chaos Space Marines
Host of Shattered Purity - Chaos Daemons