The Player's Handbook II on the feat retraining Process says that upon gaining a new level
You can exchange one of the feats you previously selected for another feat. If the new feat has prerequisites, not only must your character meet them in his current state, but you must also be able to show that he met them at the time you chose the previous feat. (193)
Rather than allowing easy access to the power psychic reformation or the Dark Chaos Feat Shuffle, I am considering implementing this slightly more conservative rule in an upcoming campaign. However, I'm concerned that it's technically exploitable by knowledgeable enough player. For example…
- The feats Cool Head (Complete Scoundrel 75-6) et al. cause the creature to "immediately learn up to two… skill tricks at no cost, and [the creature's] limit on skill tricks known increases by one." Yet once a skill trick's learned, it can't be unleared (much like having spent the skill points to gain it, below; note that a skill trick can be rendered useless if prerequisites aren't met, though). I think a creature would keep accumulated skill tricks gained this way but lose the increased capacity. (Conveniently, this eventuality is addressed by the Dragon #357 Sage Advice column “Official Answers to Your Questions” (82).)
- The feat Martial Study (Tome of Battle 31-2) may allow a martial adept to add to his maneuvers known, although this is less clear. However, given the stinginess of martial maneuvers, this exploit doesn't really bother me.
- The feat Open Minded (Complete Adventurer 111) grants the creature that takes it 5 skill points which must be spent immediately. Because most characters don't get enough skill points anyway, this exploit doesn't really bother me, either.
- The feat Shape Soulmeld (Magic of Incarnm 40) grants that creature the ability to shape one soulmeld. After the soulmeld's shaped, however, the creature need not ever unshape it, making the soulmeld a largely permanent fixture. (Although a handful of effects can forcibly unshape a soulmeld–potentially undoing several levels worth of work–, these are rare enough that the risk is likely worth the reward.) (This use of the rule raises some concerns; I'm not entirely comfortable with the entire party running around with a blink shirt (Magic of Incarnum 60-1), for instance, although that could happen anyway.)
Have I assessed the feats above accurately in light of this trade-one-feat-for-another-per-level rule? Besides trading away unwanted feats needed to meet the requirements of some prestige classes—which, unlike some, I see as an advantage to such rules—, are there other feats or exploits that by implementing this rule raise balance concerns?