ATTRIBUTES

Epoch has a good explanation of using Attributes in a conflict, which I'm going to plagiarize, with a few edits:

Rather than the styles of attributes that you may be used to, where rank in the attribute counts, or attributes are simply a bucket where you dump points into, we will go with a more standard RPG style, where there is a closed scale (in our case, 0 to 10) and you pay varying amounts of points for an attribute at a certain level.

This allows us to more precisely define the differences between the attributes. A one point difference (for example, 6 to 7) is considered a slight advantage. The more competent party will, all other things being equal, win a competition, but his victory will be neither quick, easy, nor without cost. Further, it is relatively easy to turn around a one point advantage with either secondarily important attributes or with situational modifiers. A canonical example of a one point difference in attributes might be Corwin and Eric's fight in Nine Princes in Amber. While Corwin has an advantage, he feels at one point that he will lose, and eventually, Eric is able to hold him off long enough for the guards to come.  [Note that this is Eric and Corwin we're talking about here, not their Heavy Feathers alter-egos Ptah and Set.] 

A two point advantage (for example, 6 to 8) is much more clear cut. While the two contestants are in the same general league, one has a serious advantage on the other, and will, if given some time and a relatively even playing field, probably win the contest handily and at little cost. However, it is certainly possible to turn around a two point advantage, and the more competent contestant might even do himself in if he underestimates his opponent, by, for example, pressing an attack too hard, too early. A canonical example of a two point difference might be Corwin and Benedict's fight in The Guns of Avalon. Corwin is able to ward off Benedict's attacks, and even wound Benedict slightly, but has to fight almost entirely defensively and would have eventually lost if he hadn't tricked Benedict with the black grass.

A three point difference (for example, 6 to 9) is pretty much decisive. Victory will be relatively quick and simple, and only the most herculean efforts will turn around the advantage. A canonical example might be Corwin and Strygalldwir's fight in The Guns of Avalon. Corwin handily wounds Strygalldwir several times, and then, even after suffering a reversal and being disarmed when he goes for a death blow that isn't mortal to Strygalldwir's anatomy, he's able to handily win the fight without notable injury.

Generally speaking, use of a Power will be worth no more than a point or two in a direct contest.  Powers are intended to be interesting add-ons, not make-or-break sorts of abilities, and won't make up for low Attributes.

Most members of the family have at least a 3 in every Attribute.  Normal humans rarely get above 1 in either Physique or Warfare, and never get above 0 in Temple.

There is no concept of Primary and Secondary attributes in Heavy Feathers, but Tertiary attributes exist as Foci within a stat.  For example, Khnum has Warfare 6 with a Focus in Charioteer at 8.  When fighting from his chariot, his Focus level of 8 is used, but for everything else covered by Warfare his base level of 6 applies.  It's cheaper to buy a level of a Focus than a full Attribute level (see the table at the end of the section), and you can have any number of Foci under a given attribute (more than two isn't economically wise, though).  Cost of increasing a Focus is included in the cost of increasing an attribute, so advancement can be made gradually by buying up a Focus above the Attribute level and then later paying the difference in cost to raise the Attribute as well. 

An important note: by and large, members of the Amber royal family could pass as human if they needed to.  Not so for those whose attributes reach the vastly superhuman level of 7 or above.  Such creatures could never be mistaken for human, as they take on some undeniably bestial physical appearance (most commonly the head of an animal, though other options are possible - feathers, tails, and extremely odd body types are not unheard of).  This isn't to say that such creatures couldn't find a way to disguise themselves (see Shapeshifting below), but they wouldn't have access to their superior abilities in a human form.  Mundane disguises are generally unable to conceal these features - the inhumanness is apparent to all but the most cursory look.  Also, note that bestial appearance alone does not denote an attribute of 7 or above - some folks just get born with a cow's head on their shoulders, the poor bastards.  For a list of animals typical to the setting, see the Animals page.  On to the actual attributes.

Physique is up first.  This attribute is largely unchanged from New Mutiny. It describes the ability to lift, sprint, heal, and stay awake for days on end, though it does not describe any learned skills beyond those necessary to develop such physical ability.  It plays a large role in personal combat, though an advantage of Physique will generally not match an equal advantage of Warfare when two combatants come to blows.  This varies to some degree based on combat form (in wresting, for example, Physique will nearly equal Warfare).  Physique Foci could include throwing, running, healing or ignoring pain.

Warfare is next, and slightly changed from New Mutiny's interpretation.  I don't anticipate that Heavy Feathers will be a a game of massive armies clashing together, since armies of such scale are much harder to come by in a setting where Shadow is highly unstable (see the Setting page for details).  Contests of Warfare are much more likely to occur on the personal level.  Warfare describes reflexes, accuracy, skill with weapons, as well as your ability to make terrain work for you, direct the actions of others in skirmish situations, and some higher level strategy, like managing networks of agents.  Warfare Foci could include an aspect of combat (like defense), a style of fighting (like wrestling), or skill in fighting in a particular terrain.

Now things get a bit wacky, with the Temple attribute.  As noted in the Setting page, an Amberite's temple is a place of great power for them.  The Temple attribute governs this power.  Temple has some part in granting abilities to you, but more importantly, Temple generally makes things hard on those who would invade your temple.  A high-Temple character is unassailable in their temple; to a low-Temple character, their temple is more of a comfortable place than a fortress.  Temple Foci could include unique mystical temple defenses or powerful wards against certain individuals.  

Physique

Warfare

Temple