Hmm, the vincent guess was actually kinda close actually, and it's not as metaphorical as I thought.

enduring through the worst (getting attacked enough to fill limit gauge)
and releasing the pent up fury (using a limit break (a bunch of times))
coupled with the destruction of hundreds, (thats how you get to next lim lvl)
and exploration, from sea to show, (find lvl 4 lims)
discovering the lost, perhaps hidden memories (you use it as an item to teach it to them)
to unleash the true potential (then you can use the lvl 4 limit)