Try to level up at least to 34 to get Setanta, trust me, it will be very worth it, he's one of the best physical attackers up until level 40s. Ganga level her up to 32 I think to get Mediarama, since I don't think that you have it in Yukiko yet right?.
You need to be constantly upgrading your personas, because they will always be weaker than what your current level actually needs in term of stats. King Frost is good up until level 25,26, but by level 31 you'll be needing better personas.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
