DAoC has always had a bad way to handle lag, For such reasons the server seems be tollerant to the factor "time". Meaning, when someone stays 10ft in front of you, you cannot hit him. If someone runs towards you, you might already be able to press slam at 15ft and make him stand at 10ft in front of you, because he would have run into your melee range "soon". But then cannot hit him with follow ups, because he is now out of melee range. That has always been some "strange" stuff. This obviously favours assasins and tweaking this might make it neccessary to also tweak the stealther vs. non-stealther balance. Else the time window to actually press PA from someone running with Speed VI at you would be really really close.
I have the feeling Phoenix is handling lag and how the client handles movement "prediction" pretty good, but from how the network code of the DAoC protocoll is designed, you cannot make something similar to todays more real time orientied solutions (because modern networks have a lot more bandwidth than 2002).
if you can reproduce some distinct edge cases, I am pretty sure the team wants to hear them in detail to see if they can improve the code. But I am pretty sure they have already put some sleepless nights into the code already, so they need new leads to improve the current code.