detect magic (trained only)

i suggest a change to the following use of the arcana skill:

sense the presence of magic

(i) change this from "1 minute" to the following entry:

No action required—either you notice something or you don’t. Your DM usually uses your passive Arcana check result. If you want to use the skill actively, you need to take a standard action.

i believe that this change provides characters trained in arcana to be more dynamically involved with encountered magic items and magic effects.

remember, a character who has successfully sensed the presence of magic likely will then want to identify it, which is a separate use of the arcana skill.

here is a thread on the wizards forum discussing this topic:
http://forums.gleemax.com/showthread.php?t=1165694
the discussion fleshes out the particulars