You have not actually stated any justification (good or bad) for giving a significant battle-winning advantage to someone who grinds multiple weapon skills up over someone who grinds just one.
You realize that what you are proposing could make it a requirement to multi-master to be competitive? The superior skill of a player who has played the game longer and mastered more skills should be the only advantage that player requires in one on one combat. Adding systemic advantages as well seems a bit unfair to the player who may be just as skilled but is only interested in one weapon, or perhaps has hours enough of free time only to level one up.
Surely the only justification can not be "Because it would make it feel worthwhile" for the multi-masters. If it did not feel worthwhile already, why did they do it?
You realize that what you are proposing could make it a requirement to multi-master to be competitive? The superior skill of a player who has played the game longer and mastered more skills should be the only advantage that player requires in one on one combat. Adding systemic advantages as well seems a bit unfair to the player who may be just as skilled but is only interested in one weapon, or perhaps has hours enough of free time only to level one up.
Surely the only justification can not be "Because it would make it feel worthwhile" for the multi-masters. If it did not feel worthwhile already, why did they do it?