Not necessary to reset actually. You'll benefit from the points that was allocated to your dex stat. If you are aware of it (based on your statement) STR/CRT/DEX/AGI affects the damage of lv.220 Skill.
Without the presence of it at earlier levels AGI only means evasion and aspd.
Still good, while dex raises your hit rate, atk, and reduces cooldown of your skills like hardhit.
So I don't think its a wasted points if you added agi or dex by mistake Gladiator will benefit from this stats.
Just take priority of STR/CRT as majority part of your damage comes from these.