I think that a level 75 sin can beat a 75 warrior, if he uses every trick. If the sin uses the vamp>BB>spike>thrust>pierce>bb opener then he will do enough early damage, HP pot a second before getting hit so it absorbs the first 2 hits of damage, and he must heal up during blind and during the 75 skill. Sin must also slightly over-minor so that he eventually runs out of mana, the idea being that he kills the warrior before his mana runs out. If he does that perfectly then there is no reason why a warrior should win. It is just much much easier for a warrior to play perfectly than for a sin.
Tempest, if a sin uses defense armours then it is no contest, the sin should not go below 75%. In an outlast battle, the sin will always win because the warrior will have to start alternating pots whereas the sin can keep himself alive whilst attacking permanently. It is in the warrior's interest to end the fight quickly.