My primary concern with the saber locking mechanic, let alone the concept, is how exploitable it could be in conjunction with a multitude of other factors. There are a plethora of questions that first must be addressed before even considering implementing this mechanic:
1) Will saber blocking take BP?
a) If so, how much BP will be taken and how is that going to be calculated?
b) Will the amount of BP drained be affected by saber skills/attributes/point investments?
2) How will the tangibility of the players during the clash be affected during battles/duels?
a) Does each player receive invincibility?
~ If so, how will this new mechanic be balanced in order to make it not easily exploitable in consideration of other players?
b) If not, how would players compensate in particularly chaotic environments such as ones with the presence of lamers?
c) Would a successful player that has won the clash instantaneously kill the target?
~ If not, what would happen to the target upon defeat?
3) What prevents a player from immediately clashing with the target and interrupting skillful duelists, thereby abusing the mechanic?
a) How would exploiters of this mechanic be handled?
b) Would there be an option to back out of a clash?
c) If certain styles get advantages over clashes, what stops an abuser from spamming unready targets with a clash?
These are but a few questions of mine concerning this proposed mechanism. It is not that I necessarily disagree with the implementation of a saber locking mechanic (I would support more development of dueling in general), but that there are other areas of concern for the developers that should be looked at, such as balancing maps and dueling, and having the developers focus on an entirely new mechanic would take time away needed to fix aforementioned issues.