but RMB is always used for walking, even in Combat Mode. Changing the use of RMB in one scenario would make an even bigger inconsistency imo
Well, I haven't walked myself to my death yet, so combat actions seem more crucial.
At any rate, I would suspect that most mouses have three (and generally more) buttons, surely one could have "walk" assigned to some other button. In essence, it isn't important to which *button* the action (swing from left) is mapped, but that it is made a separate function. In this case, one can remap at ones own leisure. It wouldn't even be necessary to remove the existing scheme - one could still have double swing on holding down mouse buttons and cursor movement for left swing.
The heart of my suggestion is; that swinging from the left or right, are such distinct attack patterns, that it makes sense that they should be *equally* accessible, and function in parallel fashion. Overhead e.g. is double-click (a mouse button manipulation) and does not require mouse movement either. I only suggest that the same privilege be granted the "left side swing", and it seems to me that this can be achieved without sacrificing other vital functions, or more significantly: without sacrificing player choice regarding other vital functions.
NB: The reason why I would *personally* consider LMB for left, and RMB for right swing, to be the most intuitive scheme should be obvious. With key-mapping enabled it doesn't really matter which key is used, but the fact that a function is inaccessible via simple key-press *is* significant.