I knew there must have been a good reason that these spells weren't available in AH RQ. It's fairly simple to create a character that can double their INT and POW from, say, 15 each to 30. That adds 30 to all Grimoire skills and to Manipulation. As to whether you can then cast the same spells again taking advantage of the improved duration is potentially questionable, but I wouldn't stop someone replacing their Shapechange spell with no gap between old and new, so why not allow this?
I've just realised it's even more open to abuse than I first thought. You start with 15 in each, and a Grimoire skill of 70 (30 base, +10 from Occupation, +30 Free Points). This lets you get a bonus of 7x2=14 to each, so INT and POW are now 29 each. This boosts your Grimoire skill to 98. Now you can cast them for +20 to each, which takes them to 35, bumping your Grimoire to 110. One more re-cast at +22, and your stats are now 37 each, and this does not take your Grimoire over the next 10% barrier so you're stuck with that. Your spells now can be cast to last for over 7 hours, 6h45m in the case of these two Combined spells.
I think I just won "munchkin of the week" award!
I've just realised it's even more open to abuse than I first thought. You start with 15 in each, and a Grimoire skill of 70 (30 base, +10 from Occupation, +30 Free Points). This lets you get a bonus of 7x2=14 to each, so INT and POW are now 29 each. This boosts your Grimoire skill to 98. Now you can cast them for +20 to each, which takes them to 35, bumping your Grimoire to 110. One more re-cast at +22, and your stats are now 37 each, and this does not take your Grimoire over the next 10% barrier so you're stuck with that. Your spells now can be cast to last for over 7 hours, 6h45m in the case of these two Combined spells.
I think I just won "munchkin of the week" award!