questions

whats the max block %? 70? mine stopped at 70..

Yes, 70%

so higher level shield has no use then?

If it has more defense then obviously that's useful, but otherwise no, there's no benefit.

if it has no more effect in blocks might as well put the points to str for better armors(if i want more def)

as you level it will take more and more dex to keep 70% block chance, but personally i would only keep just enough dex to keep max block and put points into str/con.

http://edmazur.com/bots/game_formulas.php

Block Chance = 25 * ( [DEX] - 50 ) / ( [Level] * 2 ) + [Shield Block Chance].

Here you can see, that more you level, more dex you will need to keep 70% blockchance.

70% is cap