When creating a Heroic Cavalier the other day, I was struck by the absolute uselessness of the paladin feats for the Cavalier. As a practical question, what elements from the paladin are useful, compatible, and desirable for a Cavalier to take? (Items, Feats, Paragon Paths, and specific builds are solicited)
In the design space of 4e, there are a number of orthogonal variables: class features, powers, items, and feats. This answer will explore traditional Paladin resources that a Cavalier can successfully exploit.
Cavs, statwise, have Str primary, Cha secondary, and a strong need for them both to be very high (18/14, 16/16 pre-racial).
In summary, there are a few interesting paragon paths and utility powers to choose from. The items that draw paladins (wepliments and radiant lightsabers) are less important to Cavs. Treat the cav as if it was a completely different class with no interaction possibilities to save time.
Class features, in many ways are a catch-all for the random fiddily bits that go along with class, paragon path, and epic destiny. (A common theme in paladin PPs is enhancing marks or granting divine sanction. If the Cav can find a MC way to mark or divine sanction, the options open up significantly) Functionally, the best thing to do here is to just multi-class out for the PP
Here, the name of the game is utility powers. I'll only be looking at blue or better powers from the handbook here.
Items, of course, depend on the main thrust of the build. This post has an excellent discussion of paladin items. There is no need for wepliments (like Vigilant Blade) or lightsabers (to insure radiant damage). Frostcheese is, as ever, a valid option. Gith Silver and psychic lock is an option, though less tasty due to the lack of a at-will synergy. Any of the charging weapons (Avalanche hammer, Vanguard weapon) will serve the Cav in good stead with her steed if she goes the charging route. The main suggestion here is look for weapons geared towards fighters rather than paladins, as there's no need for a holy symbol wepliment.
Looking at class feats only, the following is a list of feats that can be taken by a Cav. Summary: Don't even bother looking at class feats until paragon. Then grab Hero's Poise and (if a mounted charger) Holy Steed. This absolute lack of synergy is shameful.
This is a list of paladin feats that should be taken by a cav: