After weapon swap there is a small stun happening. This happens especially in intense fights when a lot is happening and especially if you have dots running on the opponent. If you wp swap then and want to follow with an ability your char is frozen for some time, maybe some parts of a second or even a second. Its like being rooted or stunned. Observed many times, not sure if its every time or only often, in no cp cyrodiil ravenwatch eu pc.
I guess that belongs to the overall combat mechanics bug but want to post it here in case nobody else did and to bring attention to it.
PC/EU
Starstréam - NB, Loveknight - HybridDK (4*), Stahlstrahlenreiter - StamDen, Azgul Grahl Bashrugk - HybridSorc (5*), Tínúvíél - StamCro, Thógard - StamPlar