You know, gender swapping magecraft isn't as silly a route to the root as one might think. Many myths describe prototypical humans as possessing aspects of both genders before being divided. So the gender bender magecraft might have been an attempt to attain that primordial state.
Hey wait a sec. One of the uses of barriers is portals(evidently). That means the fabric of space can be affected by barrier magic. That means he could set up a spatial compression/bag of holding type spell. Which means he CAN make things smaller! Gigan-chan for best girl
Triva fact, Stoats are capable of dancing in a pseudo-hypnotic manner, and once their prey(which can be many times larger) is dazed, they leap on the back and sever the spine.