Maple Shield

Alright, here's how you do the (approximate) math.

The shield above adds 22/155 = 14% to your w.att
and 12/810 = 1.5% plus 5% to your str.
In total, it adds about 21.4% to your total damage. (multiply 1.14 by 1.065)

Now suppose you get a level 71+ warrior shield and manage to scroll it to 10 w.att. It will add 10/155 = 6.5% to your w.att, which means that you need at least 15% str on it to get the same kind of damage increase as the maple shield would give you. (14 or maybe even 13% could do, depending on how much +str you get on the shield itself, but the %str bonus come in multiples of 3).

If you scroll it to 15 w.att, it will add almost 10% w.att, so you will only need 12% str on it.

And so on.

Note that the %str bonus will get less and less significant the more you get %str on your other gear. By the time you get a total of %100 str, you will need 30% str on the hypothetical 10 w.att shield, for the same overall damage bonus as you get from the maple shield. Today, that is only possible on a VIP warrior shield. After Chaos it will be entirely impossible.

So, in other words, I could use this shield as endgame? Coz I don't see myself getting a 30%STR VIP shield