Could you please help me with this poem? this is my waterloo anyway...?

Try looking on Shakespeare sites before asking on here. Well in this sonnet, 104, his last couplet is addressing future generations that the height of beauty died before they were even born. No the lines do not weaken the message. They are just fooling Shakespeare that no time has ped. The tone may be one of urance because he ures his lover that nothing about him has changed at all. But the tone could be one of solemness.