Warlock Scepter Suggestion

I was thinking about the Warlock Scepter.

The Feat Practiced Invoker isn't really fit for it to be on a weapon.

I mean, everyone who needs Practiced Invoker is likely to pick it up on their own before they can get the Warlock's Scepter themselves (on PWs that have the Warlock's Scepter available, I mean) and everyone who doesn't need Practiced Invoker it's mostly useless to.

I suggest replacing it with either Ability Focus (Invocations) or Ability Focus (Eldritch Blast) or both, if you're feeling generous.

Yeah Practiced Invoker is useless on a mace.
I remember Kaedrin saying that Maximize/Empower Spell-Like Ability does not work on items, so I believe a similar solution does not work.
Maybe making it closer to the Chasubles (permanent boost, 1d6-3d6 that costs more and maybe does not work on offhand for balance) is a better idea.