HML varies with weapon speed.
If you use this http://www.knuckleheads.dk/imbuecalc.php
and select under 'melee weapons' something slow, eg halberd, and then 'hit mana leech' and hit the 'max' button it will go very high, but if you select something faster, eg katana it will not go as far.
If you then add swing speed, it will come down further.
Here is a table:
http://www.uoguide.com/Hit_Mana_Leech
You also can reforge up to +40% to cap (154 intensity)
For example, you can reforge 70% HML/HLL on a 2.00s weapon or 100% on a weapon that 3.00s or slower.