Nostalrius Begins - Quality wow vanilla realm (1.12)

When you have 5 cp and want to deal damage I always use eviscerate because I thought it does more damage. But then I see some rogues using rupture?
Why do people use rupture if eviscerate deals more damage and it's instant?

Rupture bypasses armor but is otherwise very situational.
I usually use rupture on warriors and druids only. For warriors I just stack rupture and deadly while keeping away from melee range as much as possible. For druids the same deal when they are in bearform. Keep in mind that rupture's ticks do the same amount of damage regardless of combopoints so it's usefull to apply it when you have 1-3 points (=ruthlessness talent!). 4 or 5 points are better suited for stun/eviscerate.

Some players swear by never using Rupture and instead using only stun/eviscerate on all occasions. If you feel unsure just go with this mindset, you're not missing anything by not using Rupture.

Or on rogues to avoid their counter vanish CS or blind into first aid.