... And what is all this about paralyze and frenzy and such not working after lvl 25?
Two seperate questions. Paralize works fine. Period.
It is the mind control spells that can be a bit quirky at higher levels. Basically for them to work on enemies of higher level, you need them to be cast at 100% effectiveness (no armor). Enchanting them at max magnitude on a weapon will work fine also (regardless of your armor of course).
UESP wiki explains it here:
"Several magical effects are described in the game based upon the level of the creature that will be affected: Calm, Command Creature, Command Humanoid, Demoralize, Frenzy, Turn Undead.
Spell effectiveness is applied to the spell's original magnitude; the actual levels affected by the spell are then calculated from the resulting, reduced magnitude. Therefore, the levels shown for any spell are likely to be incorrect if your character is wearing armor. For example, Touch of Rage claims it works "up to level 18." However, if your character's Spell Effectiveness is 85%, the spell's actual magnitude will be 63.75 (75*0.85), resulting in a spell that only works up to level 15.
The maximum possible level of these spells, even at the Spell Making altar, is 25. However, the maximum strength spell, despite claiming to only work "up to level 25," will in fact work on any level enemy — as long as your character has 100% spell effectiveness. For example, casting a level 25 Command Humanoid on an NPC of level 34 will succeed. This quirk prevents these spells from becoming effectively useless for high-level characters, who will only meet creatures and NPCs with levels higher than 25. If you are wearing any armor, even with armor skills at 100, the maximum magnitude of a spell becomes 95 and therefore will only work on enemies up to level 23."
Here is the reference link: http://www.uesp.net/wiki/Oblivion:Magical_Effects#Magnitude_to_Level_Conversion
Options: Don't wear armor (easy at higher levels when you can create great enchantments, spells and potions); Enchant these effects onto weapons (except you cannot enchant with calm); Don't use mind control spells (fine for the Nord with a sword crowd, lol); Use a mod that eliminates armor penalties to spellcasting (that's what I do so Buffy can wear her modded buckskin boots 'cuz she likes how they look).