Good catch on the one class. I had meant to include it, but hadn't. It's fixed now.
As to the benefits, they're included to keep up with getting no features the class would normally have. The ultimate goal of the ritual is to let the elderly wizard be a martial warrior for a short time with just the use of magic; so he doesn't have to have amazing strength (Dangerous Combatant), heavy armor (Armored Hero), training in how to mark (Mighty Defender), or a superior dexterity (brilliant tactician).
I've also better defined what you lose in exchange for gaining them; powerful spells, accuracy, most areas of effect, and mobility respectively. Are they balanced enough to keep them? Without them, you're casting the ritual to gain 4 attack powers you can't use effectively, which makes the ritual ultimately useless without practically dedicating like a multiclass character.
The ritual is meant to let the caster become kind of a fighter (or other martial class) for a time. I agree about bringing it down to last only one encounter. I'll bring that down as well.