Fixed Bug #5085

Fixed decrease agility duration for the level 48 (used by mvps) -- It'll take the benefits of lvl 48 (e.g. rate) but the duration will be equal to the one of lvl 10.
http://hercules.ws/board/tracker/issue-5085-monster-decrease-agility/
Closes #154

Signed-off-by: shennetsind <ind@henn.et>