How do we distinguish between the names that are exclusively for Allāh from those that are not?

The names of Allah in terms of exclusiveness are divided into two categories: 1. Names that are specific to Him 2. Names that are not specific to Him The specific names of Allāh which are not permissible for anyone to use are those names that carry a meaning that is only suited to Allāh. This is determined by referring to the linguistic meaning. For example, 'Allāh', meaning the One to Whom belongs all worship and Lordship. He is the only One worthy of this trait, for none has the right to be worshipped other than Him. So it is not permissible for anyone to have adopt this as a name. It is a great crime to refer to someone as Allāh! Similarly, His name 'Ar-Rahmān', which means, the One who is characterised with vast mercy, free from any deficiency, is also another example of a name that is specific to Allah. Likewise, the name 'Al-Awwal': the First who there is nothing before Him. 'Al-Ākhir': the Last who there is nothing after Him. 'Al-Thāhir': the Most High, the One who there is nothing above Him. 'Al-Bāṭin': the Most near, the One who there is nothing nearer than Him. All of which are names that are specific to Allāh. Also, 'Thul Jalāli Wal Ikrām' and whatever resembles that from what the Arabic language indicates of meanings specific to Allāh. As for the unspecific names which may be used in reference to the creation, such as: 'Al-Azeez', Al-Kareem', 'Al-Samee', 'Al-Baseer'; then these are be used with respect to the creation in a manner appropriate to their weakness and deficiency. And with that, it is not permissible to refer to the creation with any of these names intending the complete and perfect meaning. The Prophet ﷺ heard a group of people calling a man: 'Yaa Abal Hakam' (lit. father of Judgment). He enquired ﷺ: 'why do they call you Abal Hakam?' He said: 'verily, when my people dispute in a matter, I judge between them and both parties are pleased (with my verdict)' He said ﷺ: How good this is! Do you have any sons? He said: Shurayh, Muslim and Abdul Allah. He said ﷺ: You are Abu Shurayh. The Prophet ﷺ changed his kunyah after realising that they intended its meaning. They thought so highly of him that they named him 'Abu Al-Hakam' - with its complete applied meaning, so he ordered him to change it. Similarly, if someone was to frequently honour people, it would not be allowed to name him 'Al-Kareem' (the generous one). He may be described as someone generous, but he must not be given this as a name.