yes is worth if you r not a class who cant touch the crit rate cap
lets say you are AW lvl 40 and have friend (or alt) PP lvl 52 and he have enought SP to learn hes skills for this lvl (i mean focus lvl3)
your base stat on crit may be like 45 or so
putting dagger ON (lets say crystal dagger othell 6) your crit will change to 386 or something like that
sorry dont have toon to give exact numbers
so with your PP buffing you with focus crit rate willl be 444
well lets now put othel lvl 8 on the same dagger and focus your crit rate will be 466
conclusion
with othel lvl6 you will need more crit rate buffs (like CoV or PoW) to be capped
with othel lvl8 you r fine just with focus lvl 3