Looking over your gear, I can tell you (and in a sec, show you) that you are missing the most vital stat to a multi hit ws like penta or drakesbane: ACC
Here's why: Let's figure out your total acc. You say you have 8/8 polearm correct? If capped (and it should be), you'll have 292 polearm skill. ACC from polearm is 1 acc per skill lvl from 1-200, and 0.9 acc for each over 200. So it would be 200+(92 x 0.9), which comes out to 282.8
As a hume, you should have 65 base dex, + 24 from your gear, putting you at 89 total. ACC from dex for a 2handed weapon is (dex x .75). 89 x .75 = 66.75 in your case. That puts you at 349.55 so far.
Being a DRG, you get 22 ACC from accuracy bonus II (22 acc), bringing you up to 371.55. Adding in your acc from gear (8), you're grand total is at 379.
So, why does this matter? There are two lvls of greater colibri, 81, and 82. The lvl 81s have 358 active evasion, and the 82s have 367. When your acc = mob eva, you have 75% acc. In order to cap accuracy, you need 40 acc OVER mob eva. Every 2 acc you are above or below will add or subtract 1% hit rate.
That being said... You have 379. 379 - 358 = 21. 21 puts you at roughly 85% hit rate. Not so stellar is it? And thats the lowest eva greater colibri you'll fight.
The reason this is so important is because acc is calculated for each hit of a ws. For drakesbane, it'll be .85 x .85 x .85 x .85, which is a whopping 52% chance at landing all 4 hits. For penta, you have a 44% chance at 5/5.
If you had 95% acc, it would be .95 x .95 x .95 x .95, which is an 81% chance at 4/4 drakes, and 77% chance at 5/5 penta. That's a LOT higher, and while you may not get that rare huge number ws, you'll get many MANY more big number ws, much more consistant damage, and over time you'll end up just doing way more damage than all that str can ever do for you.
TL:DR - You need about 30 more acc on ws. My recomendation would be to use ohat (or MKD helm) instead of wyvern, acc rings instead of ruby, and don't worry about the conte, Askar will serve you better. That's about 28 right there.