Are you sure there wasn't some other buff on your character when you looked at the rank 3 tooltip that wasn't there when you looked at the rank 4?
What level were you when it was at II and what level are you now that it is at IV? The game scales lower level characters up a bit but the scaling decreases as you level up until eventually it zero's out and goes away. THe higher your level the more important stat and gear scaling becomes.
Aiden_Ayzaria wrote: »If I look at the first screen, you were in Imperial City Prison, right? If you tag on random dungeon finder, you will get a buff for the whole run, depending on your role (I assume you were DPS). On the second screen, you seem out of the dungeon so I assume you had the random dungeon buff on the first screen, got your spell to level 4 with the exp gotten from that daily completion and then checked the tooltip outside after the buff was gone. It might explain why you had higher tooltip on the level 3 spell.