Sorry, i'm newbie here, but i'll try to give some answers. Just as i see.
At first, there's some trouble to answer to You. It's not because anyone wouldn't want to do that. But because any gladiator has very and very own features.
So, Adoede (for example) may have an answers for his DW-guys, but for Your DW-guys it wouldn't work fine.
At second, there is a rushing strategies like berserk 10/8 in one line. Of course, it's works fine if Your gladiator have enough agility/stamina. But a stable managers having Primus are prepared to encounter that strategy. And You must be prepared to do something against. And they must be ... And so on. :)
Third. It's looks like a destiny of Your gladiator is solved at the step of buying. It's really important which race You choose for him, his weapon, his attributes. It's not so obvious at low-level... How to choose well? Ok, You may read a guides (thanks for experienced players, who wrote it). But You must to get Your own experience to choose fine.
And Your "...my DW-strategy guys get completely destroyed by defensive parry strategies..." perhaps just a way to choose more wisely next time.
As a tip...
So, good luck to You. In the Pit.