An Idea for Knowledge Skills

As the players in my last session were searching through the books in Nagle Manor's library, it occured to me that maybe it would be a good idea to have some basic rules for knowledge acquired and that sort of thing. Here are my initial thoughts:

• A book can be studied in week-long increments. At the end of the week, the PC makes a read languages check (percentage chance equal to Greyhawk's "% chance to know spell"). If the check is successful, the PC gains a knowledge point in the particular subject, or some other benefit. If the check fails, no gain is made.
• Only one subject may be studied per character per game week. Also, only one week of study may be performed per each session played, so players that play more often will be able to make use of this more.
• Knowledge points are used in an identical manner to LotFP's skill points. Each PC has a base 1 in 6 chance of knowing something useful (to be determined by the referee). Each additional point earned through research represents an additional 1 in 6 chance of success.
• Subjects should be relatively specific, i.e. a specific monster or monster type, a specific type of potion (if trying to learn how to make one). "Magic" would not be a suitable subject, as it is too broad. Knowledge skills should never lend combat bonuses (like +1's, etc.), but they may give knowledge of certain monsters' strengths and weaknesses.
• I'm thinking 4 in 6 should be the maximum level of any knowledge skill, at least until the PCs are rather high level.
• The referee can of course modify any of these rules based on the circumstances at hand. For example, some very obscure arcane study that has a big payoff could require 4 weeks of successful research and significant monetary investment in order to gain but a single point of knowledge in that area. These are just meant as loose guidelines as a means for rewarding players that take the time to develop their characters in this way.

Here are some example subjects that PCs have already acquired books for that I would allow them to develop knowledge skills in:

• appraising art and fancy furnishings
• fishing
• ecology of oozes/slimes/jellies (would give a chance to know strengths and vulnerabilities)
• beginning magic for the mentally challenged (successful study and a minor monetary investment could perhaps lead to the learning of a random 1st-level spell or perhaps a cantrip).
• first aid (ability to make minor poultices, etc.)

Here is the read languages table I use, borrowed from Greyhawk:

Thoughts and criticisms are always welcome!