Another option is to grant the site itself a certain amount of innate power, perhaps fed by the ley lines and focused by the architecture of the temple itself, or through some specific statuary/cross/alter/etc. It would weaken the denarians, rather than strengthening a character. The difference being that its effect would be a passive, AoE thing, and not something that needs to be activated/wielded, and thus not requiring the standard IoP character requirements. Maybe it prevents the nickleheads from using their transformation abilities, or maybe it imposes a new Catch that the PCs can leverage to their advantage. Maybe it inhibits the control the Fallen can exert as they get closer to the center, so the denarians that are more dominating than partners with their host are suddenly not in control. Or maybe its not a blanket weakening, but the site is designed to support a ritual that, when triggered, does something appropriately dramatic to the denarians present, so that the site itself is a snare to trap them. Then you dont need to supercharge your PC's to the point where they can take denarians head on, instead they just need to maneuver and survive long enough to spring the trap, which then forcefully removes their coins or some such.
These are just thought on how to level the field and leverage the site, without resorting to IoP rules.