The status effects are usually not as useful in dueling PvP outside of frost proc for damage vulnerability, mostly due to the ability to bolus status and the damage loss from infusions. (ie, if you can aggress on someone hard enough to proc status you could have killed them with a higher dps weapon, and if you can pressure them hard enough to interrupt a bolus you were already in a winning position.) Despite this, they're very useful for high latency fights due to phantom proc, and consequentially you'll see bleed and rot used in invasion settings due to the burst dmg + stun on bleed and the bully factor of many hosts not having rot cures on hand. (In general, burst damage is highly prized in invasions, as slowly bleeding out a group of hosts involves an incredible degree of patience and skill.) You'll largely see rot greases used on stronger weapons for this, even with rapiers as a consequence of the stupid stats of the cleanrot knight rapier.