If they make Glaives 33, they obsolete the Onyx. If they make them 34, they risk making them uncompetitive compared to Vessery himself. Really the Onyx should have been ~30 points and the Delta ~28. Of course if they had priced them correctly in the first place we probably wouldn't be getting the new Veterans titles.
At 34, Glaives still have useful niches even with the existence of Vessery.
First, if you don't have other ships with Target Lock, or you have ships that use it badly, there's no sense in paying the point for Vessery when you can get the Glaive for less.
Second, you're already taking Vessery. In a few different threads, 2xGlaives and Vessery, all with x7 and Crack Shot (100 points total) has been thrown around. It should be really good.
Third: Third, it's a point cheaper. If the squad isn't really built to make prime use of Target Lock (but you have a ship with TL), but you still want a Defender with an EPT at PS6, you might want to put that point into a different ship or initiative. Even at the same points, Glaive/Lone Wolf or Juke/x7 for 34 points isn't a complete loser compared to Vessery/Crack Shot/x7. Looking at the 3 Defender squad referenced above, I think triple Glaives with x7 and Crack Shot (99 points, probably), beats the Glaive/Glaive/Vessery option more times than not. Because tripleG moves last, denying a first turn Target Lock, and gaining the maneuver advantage in later turns.