So, in just about every artwork of a spellcaster I can think of, the caster is holding a weapon in their off-hand and casting a spell with their main hand. This seems to indicate that the spellcaster isn't simply slinging spells all day long and implies that they, at least occasionally, use that weapon from time to time. Literary characters such as Gandalf support this, while literary characters such as Harry Potter refute this.
I was just thinking of something that might be cool, I dunno, but bear with me. Casters have spells and rituals. Spells come in a variety of level-appropriate flavors and are categorized by spell level. All spells can be cast in a single turn (be it with a swift action, and standard action, or a full-round action). After casting a spell you are unable to use spells of that level for 1d4 rounds (or 3 rounds, or 5 rounds, or something to this effect). Spells have a heavy emphasis on instantaneous effects. Rituals can't be cast in a single turn, and probably can't be cast in even as short a timespan as 1 minute. Rituals are likely also categorized by spell level, but probably don't have a limitation on how often you can cast them other than components. In this sense, spells never require material components, but rituals likely usually do. Ritual material components should then always be fairly costly. Rituals have a heavy emphasis on effects with lasting durations.
It might even be interesting to offer a Wizard character a single allotment of "Magics" known allowing them to choose between being more of a "warwizard," being more of a "bookworm", or being some combination of both.
Examples of 1st Level Spells (as per this definition of Spells)
Grease
Obscuring Mist
True Strike
Charm Person
Magic Missile
Cause Fear
Jump
Examples of 1st level Rituals
Alarm
Mage Armor
Identify
Silent Image
Enlarge Person
*Please note that while I am using the names of 3.5 spells, I am seeking only to invoke the particular concepts behind those spells, I am not necessarily suggesting that the ideas in this post be applied to the exact mechanics of those spells. Also, don't feel compelled to apply the ideas of this post only to the 3.5 edition of D&D OR to any D&D game at all for that matter.