Lonely winter as a buff that gradually increases when pet is absent, maybe replace it with a pet talent that summons a greater water elemental on a CD that does a more damage
Increase damage of ice nova
Increase damage of comet storm
Make ebonbolt baseline, replace it with a talent that lets you have 3 fingers of frost charges, and/or lets you fire them all in one global.
This way, you have a choice between more sustain from procs with frozen touch, a sustained burst from chain reaction, or a very quick, decisive, but smaller burst with the more lances in a short amount of time.
Make frigid winds or ice ward baseline, add a talent that replaces ring of frost, that is a single target instant hard CC, either deep freeze, or an incapacitate that encases a target in ice, similar to hunter trap, giving the mage a choice between powerful cross cc with ring, or shorter, quicker cc with an instant cast.
Make ray of frost have a shorter CD, like 30-45 seconds. Compare it to lightning lasso, 1.3 min is insanely long when it doesn’t even have the stun component and is easily countered.
Generally, the spec should be able to choose between a powerful, sustained frostbolt build, or a means of building up a frontloaded burst to take advantage of kill windows, which it can’t reliably do right now. Generally the control is fine, it just needs a short, quick, instant hard CC. Where fire has DB, frost needs a quick single target one for peeling, cross cc etc. These sort of changes would also add quality of life to PvE, and keep the proc management and shatter playstyle largely unchanged.