you cant switch weapons and keep TP once you switch weapons you lose all TP
and this thing does not give any extra TP when striking it only gives the effect of +100% TP when using weapon skills (IE 100% combo has the effect of 200% combo)
I bought it without even know TP bonus meant that. I thought it gave me more TP (which is store TP lol) and now that i discovered it, i am happy i bought it. Asuran fists is deadly even against jelly and elementals (so formless strikes stuff) enemies. I love this weapon.
This weapon adds 100% tp to your weapon skill, not +TP per hit. So 100% weapon skill has the effect of a 200% weapon skill, a 200% weapon skill has the effect of a 300% weapon skill, a 300% weapon skill... well you waited too long, no bonus for you.