…First up for today, it’s a quick question about Intelligent Items – and whether or not they can have levels.
…According to the SRD, Intelligent items are considered constructs. In fact, the rules refer you to the Construct type. Thus, by default, they’re immune to all mind-affecting effects, gain bonus hit points based on size (for most items that’s nothing, although two-handed weapons and such may reasonably be considered “small” for +10 HP), and gain other benefits according to their hit dice or class levels. Of course, normal intelligent items don’t have any hit dice – but the rules never tell you whether or not a sapient item that can act on it’s own can gain experience and level up. After all, pretty much everything else with an independent mind – including awakened animals and golems – can level up.
…On the other hand, that would be a fabulous pain to fiddle with – and intelligent items are already bothersome enough. Far be it from me not to provide rules for it though…
Intelligent Items are tightly bound to their current forms, to their creator’s purposes, and to their users. Thus they do not count as party members and gain experience extraordinarily slowly – so slowly that there’s no point in tracking it; it would require many centuries just to pay off the ECL penalty for their construct traits.
Intelligent items can be crafted with levels built it. 1/2/3/5/7 levels equate to a +1/2/3/4/5 special property. Of course, they may have trouble using a lot of those abilities – although they can act through their users if the user opts to allow it.
Intelligent items may also be taken as Followers. In this case, they’re considered to have a +4 ECL template – meaning that their level will be at least six levels below that of their user. Worse, at least from the items point of view, it’s abilities are limited by how much power it’s user can pour into it; lose the user, or have one who isn’t interested in empowering an item-follower, and it’s levels become unusable.
…Obviously enough, some kinds of levels are more useful than others. Not too unexpectedly for a unique entity, customized Eclipse point-buy levels are usually best. After that, psionic classes are probably best. Physically-oriented classes, such as Fighter, are usually only helpful when the user lets them take over their body.