Sunny was up against enemies whose power was well beyond his own. He was not sure what their Rank and Class were — if they could even be defined by these concepts — but both the Dark Ones and the nebulous slayer seemed far more threatening than most foes he had encountered before.
Perhaps Sunny would have been willing to attack them openly if his own powers weren't restricted, but with the Shadow Realm limiting what he could do, he was wary and apprehensive about engaging his competitors in a direct confrontation.
But that was alright.
There were many indirect ways to achieve his goal, as well. Sunny simply had to take a page from the mysterious archer's book and use all the resources available to him as tools — tools, after all, were a force multiplier that allowed one to channel their power to a much greater effect than would have been possible otherwise.