Agreed with the above posts. But if you can't wait and have plat to spare, it might be worth purchasing a deepwater bracer (assuming you are of or close to the required level). Spamming it while backed against a wall could be done to hold aggro reliably before the patch and it
should still be enough to get the job done. Of course timing its 6sec cast just right, on incoming targets, is exceedingly difficult in dungeons with poor line of sight so dps will still have to wait for the assist call.
Otherwise, might as well defer to other group members and let them adjust their playstyles for the time being, not just the stab-happy rogues but classes with deep mana pools who can cast root for proximity aggro--priests and robe wearers who are able to meditate while the mob is in camp preventing you from doing the same. Being such a common, low-level spell, root can save healer mana and everyone the frustration if it's cast straight away on the incoming target rather than as a CC reaction afterwards when aggro bounces.
A cheap alternative/addition to this strategy would be to buy a
Treant Staff. The ratio is poor, but obviously no one is going to be shocked that a knight is lacking in damage output.