Weapon discussions often refer to the "power 5" weapons:
1. paralyzing
2. smiting
3. disruption
4. banishing
5. vorpal
In addition to these, it's also useful to have greater bane weapons for commonly seen monsters that can't be insta-killed. Greater giant bane for Gianthold Tor is a prime example. Other types of bane weapons good to have around are evil outsider, construct, undead, elemental, dragon, and aberration. If this list looks familiar, it's because those are the same types of monsters(minus the last two) rangers tend to take for favored enemies.
Some monsters will also have damage reduction that require various types of weapons to bypass. This thread lists most, if not all, of them:
http://forums.ddo.com/showthread.php?t=178393
The most important types of DR to account for are the ones possessed by raid bosses: silver + holy/good and cold iron + holy/good. Both can be taken care of with the ever-popular and often expensive Metalline X of Pure Good weapons.
By crafting, I'm assuming you mean Green Steel. That's a complex topic which has its own wiki page:
http://ddowiki.com/page/Green_Steel_Item