That's actually pretty impressive you have +180 skill points to get to 900 skill; the skills themselves shouldn't be an issue but I'd be curious to see your suit (since you say it's "decent" and not elite) to see what the stats/resist are given how much skill you have added (typically this means sacrificing something).
Few questions:
What is your HP (should be as close to 150hp as possible)?
What is your Stam/SSI (are you past the max swing speed)?
What is your DCH/HCI?
Do you have refinements on your suit (if not you should)? (I'm assuming you are all 70's)
What axe are you using? --> Should be energy and use onslaught to further lower its resist
Are you using double demon slayer (tali/axe)?
Do you have HLD/HLA somewhere on your weapon/suit?
Are you using a armored swampy (or paroxy)?
It's been a while since I've fought a putrifier (I might have been using my bard as support) but typical tactic against most single targets with a sampire is to make sure your suit is all maxed out so you are swinging at 1.25 and hitting as many times as possible while getting hit less. You have the max damage part down it looks like so the other part will be to either add some HLA to your weapon to decrease getting hit while maintaining the max swing speed to keep hitting. With your max bushido/parry you can also hit evade if you get around half HP to evade most of the incoming damage and even pop a confidence to boost HP regen.