A couple posts ago is a remark about using Provoke followed by Shield Lob. Provoke gives threat+1. Almost always, if someone is surpassing you in threat, they'll pass you within moments of Provoke. Shield Lob just isn't that much emnity. Try to Provoke then use Rage of Halone, even if it's not up next in your combo. I use Rage of Halone by itself not infrequently for this reason.

If, for example, you're struggling to keep aggro on a group of 3 mobs, do the first part like you say -- Shield Lob, SW/CoS/Flash, Halone combo on #1, then swap to mobs 2/3 and hit each with Rage of Halone only (assuming DPS is mostly single-target). If you need to Provoke/Shield Lob because the mob is far from you, know that you'll need a Rage of Halone in there.