"I asked a question previously about the object of meditation being faint. [...] When trying to meditate on the breath at the aperture of the nostrils, the breath is not present and cannot be felt"
If your breath really was not present, you would be dead by now, wouldn't you?
It's important to understand that it's not the breath which is faint, it's the faculty of mindfulness that is. The breath is always there, always in a observable state.
"And how does a monk remain focused on the body in & of itself?" [...]
"Breathing in long, he discerns, 'I am breathing in long'; or breathing out long, he discerns, 'I am breathing out long.' Or breathing in short, he discerns, 'I am breathing in short'; or breathing out short, he discerns, 'I am breathing out short.' -- MN 10
So if you really can't find your breath, there is nothing wrong about it. Meditation is all about observing and letting go. Just know 'short breath' or 'subtle breath' or 'no breath'. Don't search the breath, try to be clear and present no matter what.
"no matter how much I try to arouse attention"
You named this question Lack of Grasping of the Object of Meditation. I actually think this is the problem. You're trying to grasp the object. Don't grasp. The goal is letting go which is the opposite of grasping. Concentration comes from awareness, awareness comes from surrendering to the present moment.
Understanding Right Effort
Right Effort is key for directing your mind towards the meditation object. Changing your meditation object will not help you, since both problem and solution are lying within your own mind.
Right Effort is trying without trying. If it feels like effort, it's not right effort. If it feels like no effort at all, it's still not right effort. It's about keeping the balance between dullness and restlessness, the middle way.
Also, concentration is often wrongly understood as constant applying of effort, but it's more about clarity and awareness of mind than that.
I suggest you to listen to this explanation of Right Effort by Bhikkhu Bodhi.
"Now what do you think, Sona. Before, when you were a house-dweller, were you skilled at playing the vina?" "Yes, lord."
"And what do you think: when the strings of your vina were too taut, was your vina in tune & playable?" "No, lord."
"And what do you think: when the strings of your vina were too loose, was your vina in tune & playable?" "No, lord."
"And what do you think: when the strings of your vina were neither too taut nor too loose, but tuned (lit: 'established') to be right on pitch, was your vina in tune & playable?" "Yes, lord."
"In the same way, Sona, over-aroused persistence leads to restlessness, overly slack persistence leads to laziness. Thus you should determine the right pitch for your persistence, attune ('penetrate,' 'ferret out') the pitch of the [five] faculties [to that], and there pick up your theme." -- AN 6.55