Even with Zephyr and yet another 18% Attack speed buff from Stately Dignity or Flailing Blades, Lahn's speed is nothing to be impressed about. In fact, after getting used to Black spirit's rage (common), Lahn's PvE without BSR feels clunky, slow, and often locked in animations (causing activities like Black Shrine to be harder than they should be). Therefore I suggest that the combination of these AS buffs that make up the current Lahn kit become the base AS (so that she doesnt heavily rely on BSR's attack speed buff and can obtain more AS before reaching the cap) and change the following skills:

Zephyr: Replace the AS with Evasion or Stamina. Lahn is squishy despite her HP passives and she really needs to tank damage since she has more SA than FGs. As the dancer that she is, she should be capable to smoothly waltz into battle, keeping up her mobility and evasion of enemy attacks required to sustain a fight.

Flailing blades: Personally, I would love to see this skill reworked entirely. Ive never found a use for it.

Stately Dignity: HP recover increased to 500hp (250hp is meaningless nowadays). Recover 125 Stamina every 2 seconds for 8 seconds (4 ticks in total, 500 stamina recovered over 8 seconds). The rest of the skills effects except AS remains.

Blooming Affinity: Nowadays HP bars have greatly increased compared to what they used to be. A +150hp passive is literally nothing. Replace it with Stamina or, if we want to be creative, Id love to see this skill be reworked into something more unique and original that sustains Lahn's mobility and survability. That'd be more fun than just adding flat stamina/stamina regeneration increase, but Id be more than happy to see this changed into anything thats actually useful.

Deadly Dance: I think Lahn could sustain the fight longer if Deadly Dance was a viable option to use in PvP and even PvE (assuming that you're using Core: Eradication in PvP of course. Either way, if you choose Core: Deadly Dance, I'd say this same thing but swapping the name of the skills). Therefore, perhaps it'd be a better idea to swap the Floating with the FG for Deadly Dance. That way you can still use it Deadly Dance with Core: Eradication.

Furor: Now this skill REALLY needs to have it's CC and protection swapped from the Core skills. Such a long chain of attacks at such speed is impossible to perform with 0 protection. Its even more enticing to perform this change knowing that if we do this, we dont need to choose Core: Furor to be able to make use of Flow: Dancing with Death.

Binding Chains: We arent really given a real reason to use this skill. If the target is already under CC, using a Bound CC is definitely not worth it. Perhaps removing the CC from this skill and replacing it with FG would be better, and it be very consistent with Deadly Dance's FG. (Sorry I just love using these 2 skills together).

Earthly Pain: Another chain of attacks that could be used to enhance Awk Lahn's PvE (desperately needed) but its not protected. Again Id suggest removing the CC and adding FG.

Nimbus Dismount: It would be a useful skill if we could use it smoothly at any moment of the flight (falling included) and without consuming even more stamina.

Phantom Dance/Prime: Phantom Dance: Reduce the stamina cost from 250 to 200. This is what I'd call an iframe made to counter, its not really there to help you escape (like Primrose Sprint would do) and we gain nothing from spamming it, Also its duration and distance are so short, it really isnt worth 250 stamina at all.

Bleeding Hearts/Prime: Bleeding Hearts: Greatly increase the speed of this skill. Its so slow it cant be used in combos (specially awakening because using tailspin before 2nd CC feels much more efficient).

Eradication: Change the cost from Stamina to WP. This is a skill that is often used on cooldown, and adding this extra 200 stamina every 5 seconds is not what Lahn currently needs.