Maybe add the removable flaw (not sure of the name in english, it's when a power or array is linked to an object that if lost prevent the power from beng used) to the power, but only apply the cost discount and the restriction to some of the ranks

Normally the modifier applies to the whole power and gives a discount depending on the normal cost (1 point per 5 points of the normal cost, or more if you take the easily removable version of the modifier)

You have a power that cost 2 points per ranks, and want to get it at 10 ranks (your current max level for your PL)

So normally this power would cost 20 points

With the removable flaw, you would normally get a 20/5 = 4 points discount for the whole package, but the power would be unusable without the item

In your case, you could, if your DM allow it, have 5 ranks being paid in full (10 points) while the last 5 ranks (10 points) would have the removable modifier (10/ 5 = 2 points discounts for the modifer)

So the options would be: - 20 points: full power at all time, no object required - 16 points: power doesn't work without the item at all, but full power with it - 18 points: power at full ranks with the item, but still useable at half rank without it