To summarise my position:
1. The being of the hammer, its existence, is as a physical object. It has physical properties which are intrinsic to it.
2. The hammerness of the hammer, its being a hammer as opposed to its merely being, is an extrinsic property which is added to the hammer by us. — Herg
Maybe we should agree to disagree. To modify your quote above, I would summarize my position as:
1. The being of the object-Thing as an occurrent physical object, has physical properties.
2. The being of the hammer, as ready-to-hand equipment, is of a different ontological mode than (1).
For your interest, below I have copied and pasted a very small excerpt of Heidegger's description of the phenomenology of equipment in section 15 of Being and Time.
"Taken strictly, there 'is' no such thing as an equipment. To the Being of any equipment there always belongs a totality of equipment, in which it can be this equipment that it is. Equipment is essentially 'something in-order-to...' A totality of equipment is constituted by various ways of the 'in-order-to', such as serviceability, conduciveness, usability, manipulability."
"In the 'in-order-to' as a structure there lies an assignment or reference of something to something... Equipment-in accordance with its equipmentality-always is in terms of its belonging to other equipment: ink-stand, pen, ink, paper, blotting pad, table, lamp, furniture, windows, doors, room. These 'Things' never show themselves proximally as they are for themselves, so as to add up to a sum of realia and fill up a room.
What we encounter as closest to us (though not as something taken as a theme) is the room; and we encounter it not as something 'between four walls' in a geometrical spatial sense, but as equipment for residing. Out of this the 'arrangement' emerges, and it is in this that any 'individual' item of equipment shows itself. Before it does so, a totality of equipment has already been discovered."
"
Equipment can genuinely show itself only in dealings cut to its own measure (hammering with a hammer, for example) ; but in such dealings an entity of this kind is not grasped thematically as an occurring Thing, nor is the equipment-structure known as such even in the using. The hammering does not simply have knowledge about the hammer's character as equipment, but it has appropriated this equipment in a way which could not possibly be more suitable. In dealings such as this, where something is put to use, our concern subordinates itself to the "in-order-to" which is constitutive for the equipment we are employing at the time ;
the less we just stare at the hammer-Thing, and the more we seize hold of it and use it, the more primordial does our relationship to it become, and the more unveiledly is it encountered as that which it is-as equipment. The hammering itself uncovers the specific 'manipulability' of the hammer.
The kind of Being which equipment possesses—in which it manifests itself in its own right—we call "readiness-to-hand". Only because equipment has this 'Being-in-itself' and does not merely occur, is it manipulable in the broadest sense and at our disposal. No matter how sharply we just look at the 'outward appearance' of Things in whatever form this takes, we cannot discover anything ready-to-hand. If we look at Things just 'theoretically', we can get along without understanding readiness-to-hand. But when we deal with them by using them and manipulating them, this activity is not a blind one; it has its own kind of sight, by which our manipulation is guided and from which it acquires its specific Thingly character. Dealings with equipment subordinate themselves to the manifold assignments of the 'in-order-to'. And the sight with which they thus accommodate themselves is circumspection."
"....
The ready-to-hand is not grasped theoretically at all, nor is it itself the sort of thing that circumspection takes proximally as a circumspective theme. The peculiarity of what is proximally ready-to-hand is that, in its readiness-to-hand, it must, as it were, withdraw in order to be ready-to-hand quite authentically. That with which our everyday dealings proximally dwell is not the tools themselves. On the contrary, that with which we concern ourselves primarily is the work-that which is to be produced at the time; and this is accordingly ready-to-hand too. The work bears with it that
referential totality within which the equipment is encountered."