little questions that brotherting me

well today some people told me that you uc rewards on arena lowers when you has higher rank?is this true? if true does rank affect other thing to?

another question is abbout 3-way dagger. sombody told me he got more damage on haku with a balanced str/tec bot then and unbalanced str. i always though 3 way was str based only but thinking that it a melee weapon that projectile it maybe possible it affected by both str tec.