The enchanter or alchemist class -- basically, something like a transmuter but for inanimate objects rather than animate creatures -- has been proposed a number of times, and shot down a number of times, for good reasons.

Here's an idea on how to make the class playable:

Give them abilities to enchant potions, weapons and armor, etc. but give the resulting objects durations. If permanent effects are included at all, make them have some kind of serious cost (level loss, or con loss or some such). Perhaps also give them some ability to create some simple objects.

Give objects hit points and various kinds of defenses, and redesign object destroying skills to take this into account -- give enchanters the ability to repair this damage and to enhance these defenses. Maybe introduce some specialized shoppies who can repair specific classes of objects.

For more powerful effects (for example: sharpen: significant +dam roll on edged weapons), make the effect wear off at an accellerated rate when not being carried by the enchanter, and even faster when not in the same room as the enchanter. Or, perhaps have the effect degrade in strength with time when not carried/not in same room as enchanter.

Ok, this is a lot of work, and would probably take a couple years to implement, but I think it could be made playable.