Here is a list of adds that can accumulate on your characters and where they max out.

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Hit Chance Increase:  45 (50 for gargs)  *70 will cover you for the effects of Hit Lower Attack

Defend Chance Increase:  45 + base armor (hidden bonus by armor type)  *80 will cover you for the effects of HLD

Swing Speed Increase:  60
Weapon Damage:  100
Lower Regeant Cost:  100
Spell Damage Increase:  no cap
Cast Recovery:  6
Cast Speed:  4 (2 with Chivalry)
Lower Mana Cost:  55 (40 plus 3 per piece of leather armor, or 1 per piece of plate, chain, or dragon armor)
Regens:  no cap
Reflect Physical:  105
Enhance Potions:  300
Bonus Str/Dex/Int:  no cap
Bonus Hits/Stam/Mana:  no cap

Weapon Hits:   70 + a third of value beyond 70.

(Hit lightning 100 therefore is actually Hit lightning 80:  70 + 30/3 = 80)

The first 70 count normally.  The last 30 are divided by 3 in this example, which gives 10 more.

 *Note that items that show 100 may actually be higher, but 100 is the cap that shows on gear for weapon hits,

 so trial and error will be needed to determine the true value of weapon hits that read 100.